FEDERAL AVIATION ADMINISTRATION TRANSPORT AIRPLANE AND ENGINE SAFETY REQUIREMENTS A GENERAL OVERVIEW...
-
Upload
brittany-butler -
Category
Documents
-
view
215 -
download
0
Transcript of FEDERAL AVIATION ADMINISTRATION TRANSPORT AIRPLANE AND ENGINE SAFETY REQUIREMENTS A GENERAL OVERVIEW...
FEDERAL AVIATION ADMINISTRATION
TRANSPORT AIRPLANE AND ENGINE SAFETY REQUIREMENTS
A GENERAL OVERVIEW
Certification Process Study Team Meeting #6Museum of Flight, Seattle WAJune 26-27, 2001
TABLE OF CONTENTSTABLE OF CONTENTS
• Introductory Remarks (D. Cheney)• Flight: Airplane Performance, Stability and Control,
Related Support (T. Archer/J. Neff)• Structures: Loads, Design and Construction (H.
Offerman)• Equipment: Mechanical (R. Jones)• Equipment: General, Electrical, Avionics
(S. Boyd)• Propulsion: Engine/APU (M. Fulmer)• Propulsion: Engine Installation (K. Rask)• Cabin Safety (F. Tiangsing)• Human Factors (S. Boyd)
CERTIFICATION FLIGHT TESTCERTIFICATION FLIGHT TEST
Tom Archer - FAA Flight Test Pilot John Neff - FAA Flight Test Engineer
Flight Test Branch
Seattle Aircraft Certification Office
CERTIFICATIONCERTIFICATION FLIGHT TESTFLIGHT TEST
• Overview– Flying Qualities– Systems and Equipment – Aero. Performance– Airplane Flight Manual
CDL– Operations Manual / MMEL
CERTIFICATION FLIGHT TESTCERTIFICATION FLIGHT TEST
• Flying Qualities (FAR 25, Subpart B)
• Aircraft Systems (FAR 25, Subparts D, E, & F)– Aircraft Systems– Installed Equipment
• Performance (FAR 25, Subpart B)
• Airplane Flight Manual (FAR 25 Subpart G)
FLIGHT TEST - GOALFLIGHT TEST - GOAL
• Ensure aircraft meets minimum standards– Fully operational aircraft or– with any foreseeable failures (more probable
than 1x10E-9) – with a pilot of average skills– throughout the operational envelope:
Speed Altitude Gross Weight / Center of Gravity Temperature Limit head/tail/cross winds
FLYING QUALITIES (FQ)FLYING QUALITIES (FQ)
• General Requirements-– The airplane must:
Be safely controllable and maneuverable Not require exceptional piloting skill,
alertness or strength Be capable of continued safe flight and
landing following any single failure or combination of failures not shown to be extremely improbable.
– The flying qualities requirements must be demonstrated throughout the flight envelope
FLYING QUALITIES (FQ) FLYING QUALITIES (FQ) (cont’d)(cont’d)
• Stability– Static– Dynamic
• Controllability• Maneuverability• Stall Characteristics• High Speed Characteristics• Degraded Modes
FLIGHT ENVELOPEFLIGHT ENVELOPE
• The airplane must exhibit acceptable flying qualities at the most critical loading within the ranges of speed and altitude for which certification is requested.– The airline pilot is provided with a safe operational
flight envelope (bounded by certificated limits) that has been thoroughly explored during flight testing.
– The airplane is test flown outside of it’s operational envelope to account for inadvertent excursions beyond the certificated limits.
C.G./GROSS WEIGHT ENVELOPEC.G./GROSS WEIGHT ENVELOPE
Gro
ss W
eigh
t (P
oun
ds)
Center of Gravity (%MAC)
FLIGHT ENVELOPEFLIGHT ENVELOPEP
ress
ure
Alt
itu
de
(Fee
t)
Airspeed (KCAS)
V-N DIAGRAMV-N DIAGRAM
SPECIFIC FQ FLIGHT TESTSSPECIFIC FQ FLIGHT TESTS
• General (25.101-.143)• Maneuvering stability
(25.143, .251, .255)• Longitudinal control
(25.145)• Directional and lateral
control (25.147)
• Minimum control speed (25.149)
• Trim (25.161)• Static longitudinal
stability (25.173-.175)• Static lateral-directional
stability (25.177)
SPECIFIC FQ FLIGHT TESTS SPECIFIC FQ FLIGHT TESTS (Con’t)(Con’t)
• Dynamic stability (25.181)
• Stall characteristics (25.203)
• Ground handling (25.231-.235)
• Cross wind (25.237)
• Vibration and buffeting (25.251)
• High-speed characteristics (25.253)
• Out-of-trim characteristics (25.255)
TEST CONDITIONSTEST CONDITIONS
TEST LOADING(wt/cg)
DATA
General Full range Qual, forces
Man stab “ Fs/g
Long control Heavy/fwd, aft Qual, forces
Lat-dir control Heavy/fwd, aft “
TEST CONDITIONS TEST CONDITIONS (Con’t)(Con’t)
TEST LOADING DATA
Min cont spd Light/aft Hdg, grd track
Trim Full range Control forces
Stat long stab Light/aft Fe/V
Stat lat/dir stab Light/aft Fa/, Fr/
TEST CONDITIONS TEST CONDITIONS (Con’t)(Con’t)
TEST LOADING DATA
Dyn stability Light/aft Oscillations
Grd handling Full range Qualitative
Stall char Light/aft , response
Vib/buffet Heavy/aft Fs/g, Vc, Mach
TEST CONDITIONS TEST CONDITIONS (Con’t)(Con’t)
TEST LOADING DATA
High spd char Full range Fs/g, Vc, Mach
Out-of-trimcharacteristics
Full range Fs/g, Vc, Mach
ADDITIONAL APPROVALSADDITIONAL APPROVALS
• Human Factors- continuous evaluations conducted concurrently with other tests
• Operating Limitations (FAR 25, Subpart G)- sufficient to define the envelope demonstrated during flight tests
• Airplane Flight Manual (FAR 25, Subpart G)- information validated during flight testing
SYSTEMSSYSTEMS
• Systems and equipment evaluated by Flight Test– All Systems– Virtually every piece of equipment on the A/C
Three categories of equipment> Equip. required by FAR Part 25> Equip. NOT required by FAR 25, but IS by FAR 91,
121, 125, or 135, > Equip. not required by any FAR
SYSTEMSSYSTEMS
• ALL equip. MUST meet the following rules– Perform it’s intended function/function
properly– Not provide any misleading information to
crew– Not interfere with any other equipment– Specifically applicable rules (if any)– No failure condition may preclude continued
safe flight and landing
AIRCRAFT SYSTEMSAIRCRAFT SYSTEMS
• Flight Controls• Landing Gear • Powerplant • Fuel • Auto Flight
– Flight Director– Auto Pilot – Auto Throttle– HUD
• Hydraulics
• Electrical• Pressurization/Environ.• Fire Protection• Flight Deck
– Controls– Displays
• Lights• Safety• Comm/Nav• De-ice/Anti-ice
FLIGHT TEST - FIRE/SMOKE FLIGHT TEST - FIRE/SMOKE
WATER IMPINGEMENTWATER IMPINGEMENT
COLD / HOT ENVIRONMENTCOLD / HOT ENVIRONMENT
WINDOWS / DOORSWINDOWS / DOORS
INSTALLED EQUIPMENTINSTALLED EQUIPMENT
• Operational Requirement– TCAS – GPWS/EGPWS – RWS/PWS– CVR– FDR– HF– 3rd Comm/Nav– Standby Instruments
• Optional– ACARS– GPS– IFE– Telephones– SAT Comm– Lavatories– Prayer Rooms
PERFORMANCEPERFORMANCE
• Phase of Flight– Takeoff (FAR 25.105 - .107)
Accelerate - Go Accelerate - Stop (FAR 25.109)
– Climb (FAR 25.113 - .117, .121) First / Second / Third / Final segment
– En Route (FAR 25.123)– Descent– Approach
Approach climb (FAR 25.121)– Landing (FAR 25.125)
Landing climb (FAR 25.119)
T.O. PERFORMANCET.O. PERFORMANCE
• Takeoff Speed Schedule Development (FAR 25.107)
• Takeoff Field Length Requirements (FAR 25.113)
HIGH ALTITUDE TAKEOFF PERF.HIGH ALTITUDE TAKEOFF PERF.
LaPaz, Bolivia, field elevation 13,100 ft. MSLLaPaz, Bolivia, field elevation 13,100 ft. MSL
TAKEOFF SPEEDSTAKEOFF SPEEDS
• Definitions for speed schedule development– V1 Takeoff “decision speed”
Min. speed, following critical engine failure, from which T.O. can continue and achieve 35’ within T.O. distance
Max speed to initiate the first action in an abort and stop within accel-stop distance
less than V1MBE
Brake Release Vef Vr >V2VlofV1
35 feetVmcg Vmca
Vmu
Max. tire speed
Vmbe(15’ if wet)(15’ if wet)
TAKEOFF SPEEDS TAKEOFF SPEEDS (cont’d)(cont’d)
• Definitions for speed schedule development– Vr Rotation speed
Equal to, or greater than, V1, and 1.05 Vmca result in a minimum Vlof of 1.05 OEI Vmu & 1.1 AEO Vmu Allow reaching V2min by 35’, OEI 5 knot abuse (OEI) will not significantly extend the
takeoff distance
Brake Release Vef Vr
>V2
VlofV135 feet
Vmca Vmu
TAKEOFF SPEEDS TAKEOFF SPEEDS (cont’d)(cont’d)
• Definitions for speed schedule development– V2 Takeoff Safety Speed
Meet minimum EO climb gradient Greater than V2min
– V2min 1.1Vmca 1.13Vs
Brake Release Vr
V2
V135 feet
VmcaVs
ADDITIONAL SAFETY MARGINSADDITIONAL SAFETY MARGINS
• T.O. Tests @ each flap setting– Light / mid / heavy weights– All engine / one engine inoperative– Several T/W at each flap setting– Fuel cut conditions– Overspeed– Abuses
Rapid rotations (rate) Over rotations 5 knot Vr abuse Mis-trim
• Over 60 Takeoffs
FAR TAKEOFF FIELD LENGTHFAR TAKEOFF FIELD LENGTH
“AFM” Takeoff Distance Required
Vr Vlof
35 feet
Demonstrated All Engine Distance
Takeoff Distance = 1.15 X All Eng. Dist. To 35 feet
>V2
All engine, “full up” airplaneAll engine, “full up” airplane
FAR TAKEOFF FIELD LENGTH FAR TAKEOFF FIELD LENGTH (cont’d)(cont’d)
Critical Engine Fails at Vef“Balanced” field length
“GO”
V2
VlofVr35 feet
Vef
V1
“RTO”
Throttles / max. brakes, speed brakesAFM expansion, incl. 2 sec. At V1
Dry Runway - NO credit for thrust reversersWet Runway - Credit given for thrust reversers
FAR TAKEOFF FIELD LENGTH FAR TAKEOFF FIELD LENGTH (cont’d)(cont’d)
“RTO”
VlofVr35 feet
Vef
V1
“GO”
Throttles / max. brakes, speed brakes
Vr Vlof
35 feet
Takeoff Distance = 1.15 X All Eng. Dist.
Vef
Dispatch Runway Requirement, the longest distance of:
REFUSED TAKEOFF - STOPPINGREFUSED TAKEOFF - STOPPING
• 100% MBE RTO– Demonstrated performance with:
90% (min.) worn brakes (accident investigation)> FAR 25.109
Pre-heated, 3 mile taxi w/ three stops full stop - 5 minutes
ANTI SKID - INOPERATIVEANTI SKID - INOPERATIVE
CLIMB PERFORMANCE CLIMB PERFORMANCE
• Takeoff Path Segments (FAR 25.115)– 1st = Liftoff to gear up – 2nd = gear up to 400 ft.– 3rd = 400 ft. to 1500 ft. (accel/cleanup)– Enroute = Greater of: 1500 ft. or clean, MCT & at
final climb speed
• Min. climb requirements based on: – Weight– Altitude– Temperature– Most unfavorable CG
TAKEOFF PATHTAKEOFF PATH
• Minimum Climb Gradient (FAR 25.117)– Based on total number of engines– Takeoff segment – All engine / OEI, and two EI for quads
• Operational Requirements (FAR 121, Subpart I)
ENROUTE PERFORMANCEENROUTE PERFORMANCE
• Enroute (FAR 25.123) – Following data must be determined and
published Climb performance, all engine and OEI Drift down Procedures associated with the above
APPROACH PERFORMANCEAPPROACH PERFORMANCE
• Approach Climb (FAR 25.121)– Min. climb gradient, based on:
Approach configuration Total number of engines Critical engine inoperative Max. landing weight
FAR LANDING FIELD LENGTHFAR LANDING FIELD LENGTH
Vref “landing threshold speed” Vref min = 1.23Vsr
FAR 121 “FACTORED” Landing Distance (121.195)
Touch down
FAR 121 Landing Distance = demonstrated 0.6
50 feet
transition deceleration in full braking config.
Full stop
FAR 25 Landing Field Length
landing flare
Vref
FAR 25.125FAR 25.125
AIRPLANE FLIGHT MANUALAIRPLANE FLIGHT MANUAL
• AFM (FAR 25.1581)– Four sections
Limitations Normal procedures Non-normal procedures Performance
– Appendices Configuration Deviation List Derated thrust operations Engine intermix Alternate Weight
AFM / CDLAFM / CDL
• CDL contains additional limitations required for operations with missing secondary parts– PIC notified and provided a list of all parts– Each limitation listed by placard in flight deck– Logbook entry– Cumulative performance decrements via
weight penalty
OPERATIONS MANUAL / MMELOPERATIONS MANUAL / MMEL
• Flight Crew Operations Manual (FCOM) (FAR 121.141)– Permits OM in lieu of the FAR Part 25 AFM– Must contain Limitations from AFM– Perf. data / procedures can be modified from AFM– NOT FAA Approved, “Accepted” by POI
• Master Minimum Equipment List (FAR 121.627) – Permits operation of the aircraft in a “non-standard”
configuration– owned by AEG
FLIGHT TEST - CONCLUSIONFLIGHT TEST - CONCLUSION
• Huge improvements in recent years– Analytical Methods– Dynamometer Testing– Simulation
• Only Flight Test– Total Integrated Package– Real World Environment– Human Factors
• Questions?
PART 25 STRUCTURES RULESPART 25 STRUCTURES RULES
Hank OffermanAirframe Branch
Transport Airplane Directorate
CERTIFICATION OF STRUCTURECERTIFICATION OF STRUCTURE
• CFR 14, Part 25 - Airworthiness Standards– Subpart C, Structure
Loads, design conditions, proof of structure– Subpart D - Design & Construction (Structure)
Material & process specifications, special factors, design criteria, special considerations
– Subpart G - Operating Limitations & Information Airspeed, weight, center of gravity
> Limits can not exceed values used for design in Subpart C
Instructions for Continued Airworthiness> Inspection requirements
» Locations, intervals, methods, acceptance criteria
DESIGN LOADSDESIGN LOADS
• Flight Maneuver & Gust (25.331 - 25.351)• Ground Loads (25.471 - 25.519)
– Landing loads– Ground handling loads
Taxi & ground maneuver– Towing loads– Jacking & tie-down loads
• Control Surface & System Lds (25.391 - 25.459)• Emergency Landing Conditions (25.561 - 25.563)• Supplementary Conditions (25.361 - 25.373)• Fatigue Evaluation (25.571)• Lightning Protection (25.581)
MANEUVER LOADSMANEUVER LOADS
• Response to Control Input or Command– Pilot– Automatic flight control system
• Symmetric– Balanced maneuvers
Steady state> Zero pitching acceleration
– Checked maneuvers Rational pitch vs. time profile
– Unchecked maneuvers Maximum control deflection
MANEUVER LOADSMANEUVER LOADS
• Asymmetric– Rolling conditions
Sudden deflection of controls Steady state roll maximum control
deflection– Yaw maneuver conditions
Sudden deflection of controls Overswing yaw maximum control deflection Steady sideslip maximum control deflection Sudden return to neutral
MANEUVER LOADSMANEUVER LOADS
• Airplane Flight Configuration– Cruise configuration
With and without in-flight lift and drag devices– Takeoff, approach & landing
• Airplane Weight Configuration– All critical weight & center of gravity
combinations on or within the C.G. envelope– All critical fuel load combinations
• Airplane Speed & Load Factor– All critical speed & load factor combinations on
or within the maneuver envelope
MANEUVER LOADSMANEUVER LOADS
• Load Factor - “n”– The inertial or acceleration forces acting on a
body (f) is the load factor times the weight (w) of the body
f = n x w
• Sign Convention - Airplane Axis System– Positive - push you into your seat– Negative - lift you out of your seat
DESIGN V-N ENVELOPESDESIGN V-N ENVELOPES
• Defined by Experience– Based upon extensive flight measurement
60 year history - on-going programs– Values selected such that probability of
exceedance is small– Relationships defined to ensure safe operation
in usage environment– Does not constrain airplane usage in the
operational environment– Enables minimum weight design
MANEUVER LOADSMANEUVER LOADS
• Maneuver Design Load Factors– V-n diagram
GUST LOADSGUST LOADS
• Gust is an Atmospheric Disturbance– Direction - change in angle of attack– Velocity - change in local airspeed
• Result of Gust is Change in Aerodynamic Force Acting on Airplane– Acceleration - change in load factor
• Two Structural Load Components– Rigid body response– Dynamic response due to airplane flexibility and
gust velocity profile
GUST LOADSGUST LOADS
• Present Evaluation Requirements– Discrete gust
Excites rigid body response> Provides a dynamic component
Single encounter - defined gust profile Includes airplane dynamic response
– Continuous gust Atmosphere model - power spectral density
> Atmospheric energy vs. frequency Excites dynamic components
> Provides a rigid body component Envelope design - high loads Mission analysis - fatigue spectrum
GUST ENVELOPEGUST ENVELOPE
• Gust Design Load Factors– V-n diagram
GROUND LOADSGROUND LOADS
• Ground Loads are Computed using Weights and Centers of Gravity Which Result in Maximum Design Loads in Each Landing Gear Element – Forward, aft, vertical and lateral centers of
gravity locations must be considered
GROUND LOADSGROUND LOADS
• Landing Loads– Applied to landing gear and airplane
• Landing Parameters– Descent velocity
Maximum landing weight - 10 feet per second Maximum takeoff weight - 6 feet per second
– Landing load factors Function of landing gear energy absorption
characteristics Must be validated by tests
GROUND LOADSGROUND LOADS
• Landing Conditions– Level landing (nose landing gear arrangement)
Main gear in contact, nose gear clear All three gear in contact
– Tail down landing– One-gear landing– Drift landing– Rebound landing
GROUND LOADSGROUND LOADS
• Ground Handling Loads– Taxi, takeoff and landing roll
Roughest ground reasonably expected– Braked roll
Main gear in contact, nose gear clear All three gear in contact
– Turning Side load due to centrifugal load factor
– Nose wheel yaw & steering Side load on nose gear
– Pivoting Landing gear torque
– Reversed braking
GROUND LOADSGROUND LOADS
• Towing Loads– Defines loads to be applied to the towing
fittings– 30% of the towed weight for airplanes
weighing less than 30,000 pounds– 15% of the towed weight for airplanes
weighing more than 100,000 pounds– Linearly varying between 30,000 and 100,000
pounds
GROUND LOADSGROUND LOADS
• Jacking & Tie-Down Loads– Airplanes must have jacking provisions– Loads computed at maximum ramp weight– Airplane
Loads resulting from a vertical load factor of 1.33 plus a horizontal load factor of 0.33 in any direction
– Fittings & local structure Loads resulting from a vertical load factor of
2.00 plus a horizontal load factor of 0.33 in any direction
– Tie-down fittings and local structure (IF provided) Loads resulting from a 65 knot horizontal
wind in any direction
CONTROL SURFACE & SYSTEM CONTROL SURFACE & SYSTEM LOADSLOADS
• Control Surfaces Must be Designed for Loads Resulting From– Flight conditions
Loads need not exceed those resulting from the application of maximum pilot effort loads
– Ground gust conditions– Loads parallel to hinge line
Load factor of 12 for horizontal surfaces and 24 for vertical surfaces
• Must Consider– Pilot effort effects– Trim tab effects– Unsymmetrical loading
CONTROL SURFACE & SYSTEM CONTROL SURFACE & SYSTEM LOADSLOADS
• Control System Must be Designed for Maximum Pilot Effort Loads– Aileron, wheel
80 x wheel diameter pound-inches– Elevator, wheel
300 pounds– Rudder
300 pounds• Criteria for Dual Control Systems
– Pilots acting together– Pilots acting in opposition
EMERGENCY LANDING EMERGENCY LANDING CONDITIONSCONDITIONS
• Protection of Occupants• Protection of Systems Which Could Cause
Fire or Explosion• Design Load Factors
– Up - 3.0– Forward - 9.0– Sideward - 3.0 for airframe, 4.0 for seats– Downward - 6.0– Aft - 1.5
• Dynamic Conditions for Seats– “16 g seats”
SUPPLEMENTARY CONDITIONSSUPPLEMENTARY CONDITIONS
• Engine Torque– Operating torque– Engine acceleration– Sudden engine stoppage
• Side Loads on Engine Mounts• Pressurized Compartments• Unsymmetrical Loads Due to Engine
Failure• Gyroscopic Loads• Speed Control Devices
DAMAGE TOLERANCE & FATIGUE DAMAGE TOLERANCE & FATIGUE EVALUATION OF STRUCTUREEVALUATION OF STRUCTURE
• “An evaluation of the strength, detail design, and fabrication must show that catastrophic failure due to fatigue, corrosion, manufacturing defects, or accidental damage, will be avoided throughout the operational life of the airplane” FAR 25.571(a)
DAMAGE TOLERANCE & FATIGUE DAMAGE TOLERANCE & FATIGUE EVALUATION OF STRUCTUREEVALUATION OF STRUCTURE
• Damage Tolerance Evaluation– Address catastrophic failures due to fatigue,
corrosion & accidental damage Crack growth analysis and/or tests Residual strength evaluation Inspection & maintenance procedures
– Applied to single load path structure– Applied to multiple load path and crack arrest
“fail safe” structure where it cannot be demonstrated that failure will be detected during normal maintenance
DAMAGE TOLERANCE & FATIGUE DAMAGE TOLERANCE & FATIGUE EVALUATION OF STRUCTUREEVALUATION OF STRUCTURE
• Damage Tolerance Evaluation (Cont’d)– Wide spread fatigue damage will not occur
during the design service life of the airplane Supported by full scale fatigue test evidence
• Damage Tolerance (Discrete Source)– Bird impact– Uncontained fan blade impact– Uncontained engine failure– Uncontained high energy rotating machinery
failure
DAMAGE TOLERANCE & FATIGUE DAMAGE TOLERANCE & FATIGUE EVALUATION OF STRUCTUREEVALUATION OF STRUCTURE
• Fatigue (Safe Life) Evaluation– May be used when the application of the damage
tolerance requirements is impractical• Sonic Fatigue Strength
– Sonic fatigue cracks are are not probable in flight structure subject to sonic excitation, or
– Catastrophic failure is not probable if sonic fatigue cracking occurs
• Instructions for Continued Airworthiness– The data developed to demonstrate compliance
with this requirement forms the basis for the airframe instructions for continued airworthiness
LIGHTNING PROTECTIONLIGHTNING PROTECTION
• The Airplane Must be Protected Against Catastrophic Effects of Lightning– Electrical bonding– Design of components to preclude the effect of
a strike– Diverting electrical current
PROOF OF STRUCTUREPROOF OF STRUCTURE
• 25.303 through 25.307• Computed Loads - Limit Loads• Limit Loads Times Factor of Safety -
Ultimate Loads– Factor of safety - 1.5
Very low number - commercial machine design applications use 6 and up
Usage is justified by material and process controls imposed by Subpart D and maintenance programs required by operating rules> Part 91, 121, 125, 135
PROOF OF STRUCTUREPROOF OF STRUCTURE
• Requirement– Limit load
No detrimental permanent deformation Deflections may not interfere with safe
operation– Ultimate load
Structure must be able to support the load for 3 seconds
– Dynamic testing may be used
PROOF OF STRUCTUREPROOF OF STRUCTURE
• Compliance Demonstration– Static tests to limit load
May require ultimate load testing where limit load testing is determined to be inadequate
– Structural analysis May only be used if the structure conforms
to that for which this method has been shown to be reliable
DESIGN AND CONSTRUCTIONDESIGN AND CONSTRUCTION
• Material & Process Specifications– 25.603, 25.605, 25.613
• Special Factors– 25.619 - 25.625
• Design Criteria– 25.607 - 25.611, 25.651 - 25.735
• Special Considerations– 25.629 - 25.631, 25.843(a)
MATERIAL & PROCESS MATERIAL & PROCESS SPECIFICATIONSSPECIFICATIONS
• The Suitability and Durability of Materials Must - – Be established on the basis of experience or
tests– Conform to approved specifications
Ensure having the strength and other properties assumed in the design data
Take into account environmental conditions expected in service> Temperature> Humidity
MATERIAL & PROCESS MATERIAL & PROCESS SPECIFICATIONSSPECIFICATIONS
• Manufacturing Processes– The method of fabrication used must produce
a consistently sound structure– If a fabrication process requires close control
to produce consistently sound results it must be performed under an approved process specification
– Each new fabrication method must be substantiated by tests
MATERIAL & PROCESS MATERIAL & PROCESS SPECIFICATIONSSPECIFICATIONS
• Material Specifications– Material strength properties must be based on
enough tests of material meeting approved specifications to establish design values on a statistical basis
“A-basis” – 99% probability, 90% confidence “B-basis” – 90% probability, 90% confidence
– Effects of temperature must be considered where thermal effects are significant under normal operating conditions
SPECIAL FACTORSSPECIAL FACTORS
• The Factor of Safety of 1.5 Must be Multiplied by the Highest Pertinent Special Factor of Safety for Each Part of the Structure Whose Strength is– Uncertain– Likely to deteriorate in service– Subject to appreciable variability
Uncertainties in manufacturing process Uncertainties in inspection methods
SPECIAL FACTORSSPECIAL FACTORS
• Casting Factor – Process Variables– Critical castings
Failure would preclude continued safe flight and landing or cause injury
1.25 to 1.5> Based upon testing and inspection
– Noncritical castings All others 1.0 to 2.0
> Based upon testing and inspection
SPECIAL FACTORSSPECIAL FACTORS
• Fitting Factor – Uncertainties in Stress Analysis– Applied to fittings whose strength has not been
proven by limit and ultimate load tests– 1.15
• Fitting Factor – Wear and Deterioration– Seats, seatbelt fittings– 1.33
• Bearing Factor – Wear and Deterioration– Control surface hinges– 6.67
SPECIAL FACTORSSPECIAL FACTORS
• Bearing Factor – Clearance Fits Subject to Vibration– Judgment
• Joints Subject to Angular Motion – Wear– 3.33– Not applicable to ball or roller bearings
DESIGN CRITERIADESIGN CRITERIA
• Fasteners– Locking devices
• Protection of Structure– Protection against loss of strength in service
due to any cause, including Weathering Corrosion Abrasion
– Provisions for ventilation and drainage
DESIGN CRITERIADESIGN CRITERIA
• Control Surfaces– Limit load tests required– Compliance with special factor requirements
must be shown by analysis or test• Control System Stops
– Must be able to withstand any load corresponding to design conditions for the control system
• Control system Limit Load Static Tests– Testing required in which
Each fitting, pulley and bracket is loaded Compliance with special factors may be by
analysis
DESIGN CRITERIADESIGN CRITERIA
• Landing Gear– Shock absorption tests
Limit drop tests> Landing load factors
Reserve energy absorption drop tests> 12 foot per second descent velocity
• Landing Gear Retracting Mechanisms– Loads from flight conditions, gear retracted– Loads from flight conditions in landing
configuration, gear retraction operating
DESIGN CRITERIADESIGN CRITERIA
• Landing Gear Doors– Design for yawing conditions
• Wheels and Tires– Requirements for load ratings
SPECIAL CONSIDERATIONSSPECIAL CONSIDERATIONS
• Aeroelastic Stability Requirements– Flutter, divergence, control reversal– Loss of stability and control as a result of
structural deformation– Must be shown by
Analysis Wind tunnel tests Ground vibration tests Flight tests Other means found necessary by the
Administrator
SPECIAL CONSIDERATIONSSPECIAL CONSIDERATIONS
• Aeroelastic Stability Requirements (Cont’d)– Aeroelastic stability envelope
Normal conditions> VD + 15%
Failure, malfunction & adverse conditions> VC + 15%> Failures, malfunctions & adverse conditions defined
– Flight test requirements• Bird Strike
– Empennage 8 pound bird at VC
Robert C. JonesMechanical Systems Branch
Transport Airplane Directorate
MECHANICAL SYSTEMSMECHANICAL SYSTEMS
MECHANICAL SYSTEMSMECHANICAL SYSTEMS
• Flight Controls
• Hydraulic Systems
• Landing Gear Systems
• Cabin Environmental Systems
• Cargo Fire Protection Systems
• Ice Protection Systems
FLIGHT CONTROL SYSTEMSFLIGHT CONTROL SYSTEMS
Flight Control Systems (25.629, .671, .672, .1309 et al)• Ensure airplane controllability for
– All flight and load conditions in flight envelope– Environmental conditions (temp, precip, salt, deice contamination, etc)
– In the presence of failures (including A/P) All single failures & combinations of
failures Pf > 10^-9 and certain dual failures Jams Pj > 10^-9
– Ensure availability of functions that rely on FC Stability: Flutter, speed, mach, dutch roll; load
allev. Safe pilot interface (feel systems, disconnects,
indications, warnings, motions, procedures)• Methods: Test, analysis redundancy, separation, monitoring,
maintenance
FLIGHT CONTROL SYSTEMSFLIGHT CONTROL SYSTEMS
Safety Objectives• Provide control system capable of safely maneuvering airplane
through all phases of flight within the flight envelope and that has effective residual control for safe flight and landing after failures and jams.
• The system must be designed to allow to control airplane without exceptional piloting skill or strength even after failures.
• System design must account for human factors to ensure pilot has suitable warnings, can disconnect or override interfacing systems, and that movement of controls in the normal sense results in normal airplane response.
• Where automated functions (A/P, SAS, LAS) implemented thru flight controls ensure system has acceptable reliability, annunciation, disconnects, and that procedures are available to permit CSF&L.
• Ensure the airplane without engines remains controllable down to certain landing speeds.
FLIGHT CONTROL SYSTEMSFLIGHT CONTROL SYSTEMS
Upcoming Improvements
Harmonized flight control rule (25.671/672) • Addresses NTSB recommendation for reliable
redundancy• Ensure that failures of dual redundant control
paths do not fail latent without meeting specific guidelines
HYDRAULIC SYSTEMSHYDRAULIC SYSTEMS
Hydraulic Systems (25.1309, 1435, 1438, 1461)
• Ensure hydraulics for critical & essential services
• Equipment req’d to meet specific pressure loads in combination with limit structural loads and to withstand 1.5 X design operating pressure load
• Fire safety requirements
• Integrity of pressure vessels
• Containment of failed rotors
• Methods: Test, analysis, separation, redundancy, monitoring, maintenance
HYDRAULIC SYSTEMSHYDRAULIC SYSTEMS
Safety Objective
• Ensure hydraulics for critical & essential services, as required, to allow continued safe flight and landing even after hydraulic failures
LANDING GEAR SYSTEMSLANDING GEAR SYSTEMS
Landing Gear Systems (25.721, 729, 735, 1309, JAR 25.745)
• Provide capability for airplane ground maneuvering,
• Braking/stopping, • Gear retraction and gear extension in the
air.
LANDING GEAR SYSTEMSLANDING GEAR SYSTEMS
Safety Objective
• Provide capability for airplane ground maneuvering, braking/stopping, plus gear retraction and gear extension in the air
– Landing gear systems include nose and main gear retraction/extension mechanisms including doors, wheels, tires, brakes and brake controls (antiskid), steering, brake wear & temperature monitoring, and tire pressure indication systems
LANDING GEAR SYSTEMSLANDING GEAR SYSTEMS
Note
• Worn Brake Rejected Take-Off (RTO)
– A DC-10 went off the runway. Brakes had been tested in a new condition for RTO in accordance with the certification rules in effect at that time. AD required airplanes over 75,000 pounds to perform a worn brake demonstration(dynamometer)
– Latest rule requires airplane demonstration for all gross weights
Cabin Environment (25.831, 25.832, 25.841, 25.1438, 25.1441, 25.1443, 25.1445, 25.1447, 25.1450, 25.1309)
• Ensure passengers and crewmembers have:
– an acceptable environment during normal operating conditions
– adequate protection to enable survival without permanent physiological damage after any system failure
• Methods: Test, analysis, redundancy, maintenance
CABIN ENVIRONMENTAL SYSTEMSCABIN ENVIRONMENTAL SYSTEMS
Safety Objective
• Provide the means to keep the occupants of the aircraft alive and comfortable
– Oxygen, pressurization, pneumatic, heating, ventilation, and air conditioning systems
CABIN ENVIRONMENTAL SYSTEMSCABIN ENVIRONMENTAL SYSTEMS
CABIN ENVIRONMENTAL SYSTEMSCABIN ENVIRONMENTAL SYSTEMS
• The pressurization and temperature controlled environments protect the occupants from the cold temperatures at high altitudes and provides an atmosphere with enough oxygen to maintain life
• The high operating altitudes of modern aircraft necessitate oxygen systems that can sustain life for a limited period of time should cabin pressurization fail
Cargo Fire Protection (25.851(b), 25.855, 25.857, 25.858, 1309)
• Ensure that - – Detection systems detect a fire before it
damages airplane structure & provides visual indication within 1 minute
– Built-in fire extinguishing system does not introduce a hazard to occupants or the airplane structure & is adequate to control any fire likely to occur
• Methods: Test, analysis, redundancy, maintenance
CARGO FIRE PROTECTION CARGO FIRE PROTECTION SYSTEMSSYSTEMS
Safety Objectives
• Provide safety features to detect/combat fires
• Minimize the impact of fire and extinguishing agent on occupants
CARGO FIRE PROTECTION CARGO FIRE PROTECTION SYSTEMSSYSTEMS
• Cargo Compartments
– Requirements to keep hazardous quantities of smoke/flame from entering into crew/passenger compartments
– Most are required to have smoke/fire detectors and an annunciator in the flightdeck
• Fire Suppression
– Cargo compartment fires are not “extinguished,” they are “suppressed and controlled”
– The suppressing agent is Halon
CARGO FIRE PROTECTION CARGO FIRE PROTECTION SYSTEMSSYSTEMS
CARGO FIRE PROTECTION CARGO FIRE PROTECTION SYSTEMSSYSTEMS
• Information on Class D to C Cargo Compartments
– FAA eliminated Class D cargo compartments for future type certification from commercial transport airplanes March 19, 2001
Class D cargo compartments must meet the standards for Class C or Class E compartments
These changes came about because of a number of
accidents, including Valujet
ICE PROTECTION SYSTEMSICE PROTECTION SYSTEMS
Ice Protection (25.1419, 1403, 1309)
• Ensure Airplane Safety by:
– Detection ice or icing conditions– Anti-ice or deice capability– Windshield and probes heating – Provide acceptable flight characteristics for
intercycle ice and ice accreted on unprotected surfaces
• Methods: Test, analysis, redundancy, separations
ICE PROTECTION SYSTEMSICE PROTECTION SYSTEMS
Safety Objectives• For airplanes that intend to operate in icing conditions
the ice detection and protections systems must be designed to ensure timely activation and capability of ice protection system, the airplane must be shown to safely operate with ice accreted on unprotected surfaces and intercycle ice on protected surfaces, and the airplane must be shown safe for trajectories of shed ice to ensure they do not negatively impact propulsion, instruments, or structures
• Clear windshield in icing conditions• Instruments operable in icing conditions
ICE PROTECTION SYSTEMSICE PROTECTION SYSTEMS
• Developments– Definition of SLD conditions for certification.
Current FAR/JAR do not cover this condition. (rule in development)
– Detection of ice formations aft of the protected surfaces. Current FAR/JAR do not require this. (OPS rule in development)
– Ensuring stall margins met with intercycle ice and ice on unprotected surfaces (SFAR in work)
PART 25 EQUIPMENT RULESPART 25 EQUIPMENT RULES
Steve BoydSystems & Flight Crew Interface Branch
Transport Airplane Directorate
OVERVIEWOVERVIEW
• General Remarks• Equipment Installation Requirements• Safety Standards and Objectives• Operational Environment• Instruments• Electrical Systems• Lighting• Recording Systems
GENERAL REMARKSGENERAL REMARKS
• Subpart F addresses most systems installed in the airplane
• Examples include – avionics – flight and navigational equipment – environmental control – lighting– power generation
EQUIPMENT INSTALLATION EQUIPMENT INSTALLATION REQUIREMENTSREQUIREMENTS
• Overall Purposes – Establish safety standards for installed equipment
Equipment must perform its intended functions Regulate frequency of failures based on their
severity Protect aircraft and persons against effects of
environmental and operational hazards Provide means to alert the crew
– Standardize certain flight deck display information– Provide airworthiness standards for certain
equipment required by operating rules
SAFETY STANDARDS: PERFORM SAFETY STANDARDS: PERFORM INTENDED FUNCTIONINTENDED FUNCTION
• The equipment’s functionality, capability, and limitation must be deliberately incorporated, i.e. no hidden functionality (25.1301)
• Certain levels of reliability for safety-critical systems are required,…
• However, equipment is not expected to always work
• Therefore, the effects of failures are also regulated (25.1309)
SAFETY OBJECTIVESSAFETY OBJECTIVES
Catastrophic Effect
Minor Effect
Extremely Improbable
More Frequent
Reduced Crew Ability to Cope with Adversity
Improbable
• Failure effects are regulated by requiring an inverse relationship between the severity of the failures and their frequency of occurrence
SAFETY OBJECTIVESSAFETY OBJECTIVES (continued)(continued)
In addition…• Fail Safe Design = No single failure
can result in a catastrophic condition (AC25.1309-1A)
SAFETY OBJECTIVESSAFETY OBJECTIVES (continued)(continued)
• The regulations governing system safety are based on the “fail-safe” design concepts which typically include:– Design integrity and quality (design practices)– System redundancy (protect from first failure)– Proven reliability (service experience)– Error tolerance (designer, maintainer, operator)– Flight/maintenance crew procedures (mitigate
failure effects)– Others (not listed for brevity)
SAFETY OBJECTIVESSAFETY OBJECTIVES (continued)(continued)
• The safety objectives are defined at the airplane level, not at the components themselves [a component failure does not always result in a hazard to the airplane, crew, or occupants]
• To meet these objectives, the methods of compliance routinely involve qualifying components by rigorous industry-wide guidelines:– Hardware RTCA/DO-160D– Software RTCA/DO-178B
• Alerting is necessary to meet the overall safety objectives (25.1309 (c)) – When flight crews are expected in intervene to
mitigate the effects of failures– Alerting can be by design (warnings/cautions)
or by intrinsic characteristics (e.g. deterrent buffet)
• Lighted messages are standardized by color coding: red or Amber, depending on the hazard level and urgency (25.1322)
SAFETY OBJECTIVESSAFETY OBJECTIVES (continued)(continued)
SAFETY OBJECTIVESSAFETY OBJECTIVES (end)(end)
• Certification Maintenance Requirements (CMR) are established during certification as an operating limitation of the Type Certificate (AC25-19)– CMR is failure finding task to detect safety-
significant latent system failures that, in combination with other failures, result in a hazardous or catastrophic condition
– CMR is not MSG-3 which are tasks that prevent failures
– CMR is not structural inspection required by 25.571, 25.1529, Appendix H25.4
THE OPERATING ENVIRONMENTTHE OPERATING ENVIRONMENT
• Effects due to operational and environmental conditions (internal and external) are considered – Specific rules for:
lightning protection (25.1316) ice detection and protection (25.1403, 1419) life support systems (25.1438-1453)
– Other conditions (altitude, temperature, rain, wind, vibration, glare, etc…) are considered in specific methods of compliance which typically involve testing
INSTRUMENTSINSTRUMENTS
• The regulations provide the minimum standards for displaying safety-critical information in the flight deck (25.1303, 1305)
• Certain instruments must be installed– Safety-critical flight and navigation
instruments (specific navigation systems are required by operating rules)
– Powerplant instruments• The “basic T” arrangement (25.1321)
INSTRUMENTSINSTRUMENTS
• Specific regulations levied against flight critical system to ensure:– Safety of design (under failure conditions, for
flammability, system status indications, etc.)– Human factors issues (control accessibility,
consistency of operation, consistent use of color, etc.) have been addressed
– Adequate means to detect system failures – Adequate system capacity (for electrical
power)
INSTRUMENTSINSTRUMENTS
• General requirements levied against flight critical instruments ensure:– Means are provided to connect required
instruments to opposite side of cockpit– Display of information essential to safety of
flight will remain available to pilots after single failure
– Other systems may not be connected to these flight critical systems, unless provisions are made to ensure correct operation after failure
AIRSPEED INDICATING (25.1323)AIRSPEED INDICATING (25.1323)STATIC PRESSURE (25.1325)STATIC PRESSURE (25.1325)
• Other specific instrumentation requirements intended to deal with past problem areas:– System arrangement to prevent malfunction due to
entry of moisture, dirt, or other substances– Heated to prevent malfunction due to icing – Redundant systems separated to prevent single
event (e.g., birdstrike) from disabling multiple systems
– Positive drainage to avoid corrosion, correct use of materials, correct installation to avoid chafing
AUTOPILOT/FLIGHT DIRECTOR AUTOPILOT/FLIGHT DIRECTOR SYSTEMS (25.1329)SYSTEMS (25.1329)
• Must be able to be disengaged quickly and positively to prevent interference with pilot control of airplane
• Must be designed to prevent hazardous loads on airframe or hazardous flight path deviations during normal flight or failure condition
• Must be designed to provide positive and unambiguous annunciation of current operating mode
• Human factors issues (operation of controls, location of displays and controls, etc.)
POWERPLANT INSTRUMENTS POWERPLANT INSTRUMENTS (25.1337)(25.1337)
• Provides installation requirements for the instruments required by other sections– Minimize hazards from escape of flammable
fluids– Ensure proper calibration of fuel quantity
indication systems– Minimize affects of fuel flowmeter
malfunctions– Other specific issues associated with oil
quantity, propeller position, and fuel pressure indication systems
ELECTRICAL SYSTEMSELECTRICAL SYSTEMS
• General Requirements
• Generating Systems
• Distribution System
• Circuit Breakers
GENERAL REQUIREMENTSGENERAL REQUIREMENTS
• The airplane must be capable of operation without normal electrical power sources at maximum altitude for at least 5 minutes (25.1351d)
• Electrical equipment, controls and wiring must be installed to ensure non-interference with other electrical units and systems essential to safe operations (25.1353a)
• Electrical cables must be grouped, spaced and routed to minimize damage to essential systems due to faults in heavy current-carrying cables (25.1353b)
GENERAL REQUIREMENTSGENERAL REQUIREMENTS
• Electrical Systems Laboratory Tests (25.1363)– system should have a high degree of fidelity
with actual equipment installed on the airplane– for flight conditions not simulated adequately
in the laboratory, flight tests must be made example: effect of zero g and negative g’s
on generator function
GENERATING SYSTEMS (25.1351)GENERATING SYSTEMS (25.1351)
• Electrical Loads analysis determines the generating capacity and number and kind of power sources
• No failure of a power source can create a hazard or impair the ability of remaining sources to supply essential loads
• There must be a means to disconnect power sources from the system and indicate power available
BATTERIES (25.1353C)BATTERIES (25.1353C)
• Most aircraft need a battery to power critical systems or start the auxiliary power unit in case normal generator power is lost in flight
• Battery requirements include:– temperature and pressure safeguards– protection from explosion and toxic gas emissions– meet 5 minute loss of primary power requirement– charge rate, temperature monitored with
associated warning to crew and ability to disconnect
CIRCUIT PROTECTION (25.1357)CIRCUIT PROTECTION (25.1357)
• Circuit breakers or fuses are required to protect wiring and airplane power busses– automatic devices required to minimize hazard
to airplane in event of wiring faults– protective devices necessary for generating
system– if resetting is required for safety of flight,
circuit breaker must be located and identified so it can be easily reset in flight
LIGHTING REQUIREMENTSLIGHTING REQUIREMENTS
• External requirements include:– Position lights (red, green, white on tail)
(25.1385, 1387, 1389)– Anti-collision lights (25.1401)– Wing ice detection lights (25.1403)– Landing lights (25.1383)
• Specific requirements for coverage, color, position and intensity (25.1389, 1391, 1393, 1395, 1397)
LIGHTING REQUIREMENTSLIGHTING REQUIREMENTS
• Internal lighting requirements include:– means provided to control intensity (25.1381)– meet intended function (25.1301)– emergency lightning for evacuation (25.812)
• Cockpit lighting evaluation by pilots for all operational conditions
• No requirements for cabin lights, except for emergency lighting
RECORDING SYSTEMSRECORDING SYSTEMS
• Recording systems must not impact the safe operation of the airplane and are mandated by the operating rules (91.609 c,e)
• Design and installation requirements addressed in Part 25, subsection F– Cockpit Voice Recorder (CVR)– Flight Data Recorder (FDR)
• Additional requirements in operating rules (121.359, 121.343)
MISCELLANEOUS EQUIPMENT MISCELLANEOUS EQUIPMENT REQUIRED BY OPERATING RULESREQUIRED BY OPERATING RULES
• Airworthiness standards for certain equipment required by operating rules are provided– Windshear systems (121.358, AC25-12)– Protective breathing equipment (25.1439)– Oxygen equipment (25.1441-1453)– Terrain Awareness & Warning (TAWS)
(121.354, AC25-23)– Traffic Alert & Collision Avoidance System
(TCAS) (121.356)
ENGINES AND APU’SENGINES AND APU’S
Mark FulmerManager, Engine Certification Office
Engine and Propeller Directorate
FUNDAMENTAL CERTIFICATION CONCEPTSFUNDAMENTAL CERTIFICATION CONCEPTSENGINES AND APU’SENGINES AND APU’S
• Safety is defined at the Aircraft level
– Engine and APU Contributors
Burst
Fire
Loads
Loss of Thrust Control
Toxic Products in Bleeds
In-flight Shutdown
Propeller Release
Typical averageby PAH type
Wide variationsubjective criteria
Priority
ResourceExpenditure(degree ofattentionpaid)
THE OLD WAYResources Expended on Initial & Ongoing Evaluation (Type & Production)
THE OLD WAYResources Expended on Initial & Ongoing Evaluation (Type & Production)
No Distinction for Same Production Approval Holder (PAH) types PMA/TSO/PC)
{
THE NEW WAYResources Expended on Initial & Ongoing Evaluation
(Type & Production)
THE NEW WAYResources Expended on Initial & Ongoing Evaluation
(Type & Production)
Smaller variationdefined by resourcetargeting
ResourceExpenditure(degree ofsafety basedattentionpaid)
Priority
Old Avg.
Non-PriorityNon-Critical
Designees &Self Audit
PriorityNon-Critical
PI/PE Evaluations
PriorityCritical
ACSEP & ProductSpecific Evaluations
Focus
Eval. Method
System AdequacyCriteria
{{{
Determined by: - SVC Exper Safety Data - Product Safety Assessment
Causal Factors of Disk Causal Factors of Disk FracturesFractures
Accident (level 4)
Part Fractures
Hazardous events:~ 16 per 100 M flights
All uncontained:~ 32 per 100 M flights
low cyclefatigue
high cyclefatigue
manufact.defect
materialdefect
maint. &overhaul
fretting/rubbing
erosion/corrosion
bearingfailure
overspeed overtemp FOD
ForgingMachiningPeening
TitaniumInconelSteelOther
Assembly errorInspectionRepairtroubleshooting
Loss of diskcooling,Limitationexceeded
Shaft failureFuel ControlClosed VSVs
Examples
Opportunities
~ 5 per 100 Million Flights
Opportunities
DesignProd.Maint.
BirdsA/C ice shedBlue iceBMOD
FUNDAMENTAL CERTIFICATION CONCEPTSFUNDAMENTAL CERTIFICATION CONCEPTSENGINES AND APU’SENGINES AND APU’S
• Some common considerations
– Likely single and multiple failures
– Likely improper operation
– Likely improper maintenance
– Likely inservice damage
– Minimize and cover latent failures
– Human factors assessed
FUNDAMENTAL CERTIFICATION CONCEPTSFUNDAMENTAL CERTIFICATION CONCEPTSENGINES AND APU’SENGINES AND APU’S
• Burst
– Minimize failures that can release debris, particularly high energy debris
– Contain failures where possible
– Uncontainable failures are predictable
– Effects on aircraft minimized (redundancy, isolation, shielding)
FUNDAMENTAL CERTIFICATION CONCEPTSFUNDAMENTAL CERTIFICATION CONCEPTSENGINES AND APU’SENGINES AND APU’S
• Fire– Minimize occurrence and spread
Contain flammable fluids
> Assess structural integrity and materials of components and fire wall
Isolate ignition sources
Control usage of flammable materials such as Titanium and Magnesium
Coordination with aircraft installation to minimize effects
FUNDAMENTAL CERTIFICATION CONCEPTSFUNDAMENTAL CERTIFICATION CONCEPTSENGINES AND APU’SENGINES AND APU’S
• Loads– Ultimate and limit capability defined
Mounts Major load carrying structure
– Vibratory (internal and external effects) Component criticals and induced
– Failure conditions Instantaneous, rundown, windmilling
– Engine induced loads coordinated with aircraft installation
FUNDAMENTAL CERTIFICATION CONCEPTSFUNDAMENTAL CERTIFICATION CONCEPTSENGINES AND APU’SENGINES AND APU’S
• Loss of Thrust Control – Control system reliability and safety
assessment (hardware and software)
– Redundancy channels, mode, models, hydro-mechanical
backup
– Auto-shutdown for APU’s
– Limiting topping, overspeed, overtemp
– Fail safe options
FUNDAMENTAL CERTIFICATION CONCEPTSFUNDAMENTAL CERTIFICATION CONCEPTSENGINES AND APU’SENGINES AND APU’S
• Toxic Products in Bleeds
– Bleed air quality testing
– HazMats and VOC assessment
– Minimize ingress for likely failures
– Aircraft level isolation
FUNDAMENTAL CERTIFICATION CONCEPTSFUNDAMENTAL CERTIFICATION CONCEPTSENGINES AND APU’SENGINES AND APU’S
• In-flight Shutdown – Reliability and durability
Random independent vs. common cause threat Damage tolerance ETOPS Control system time limited dispatch
– Environmental Weather, birds, HIRF, lightning
– Stability Fan and compressor stall Combustor stability
– Human factors in operations and maintenance
FUNDAMENTAL CERTIFICATION CONCEPTSFUNDAMENTAL CERTIFICATION CONCEPTSENGINES AND APU’SENGINES AND APU’S
• Propeller Release
– Propeller mount flange and shaft loads
– Propeller installation and flight strain survey evaluated for suitability
FUNDAMENTAL CERTIFICATION CONCEPTSFUNDAMENTAL CERTIFICATION CONCEPTSENGINES AND APU’SENGINES AND APU’S
• Outcomes of Certification– Ratings and Operating Limitations
Power Rotor speeds Temperatures and pressures (gas path, fuel,
oil, etc.)
– Installation Requirements Component temperatures Loads (steady & vibratory) Inputs/Outputs
FUNDAMENTAL CERTIFICATION CONCEPTSFUNDAMENTAL CERTIFICATION CONCEPTSENGINES AND APU’SENGINES AND APU’S
• Outcomes of Certification– Operating instructions
Altitude, attitude, speed, temperature Procedures (in-flight relight, environmental,
ground handling, etc.)
– Airworthiness Limits Component life, inspections, maintenance
– Instructions for Continued Airworthiness On-wing preventative maintenance and
off-wing overhaul
FUNDAMENTAL CERTIFICATION CONCEPTSFUNDAMENTAL CERTIFICATION CONCEPTSENGINES AND APU’SENGINES AND APU’S
• Production Certification
– Production process definition, process controls, defect characterization, inspectability, surveillance
• Operational and Maintenance Certifications
– Based on ability to adhere to type certification data, limitations, and conditions
• Ongoing Management of Production, Operability and Maintainability
FA ACT SECTION 603FA ACT SECTION 603
• To be eligible for an airworthiness certificate, an aircraft must:
– Conform to its type certificate, and
– Be in a condition for safe operation
• Type Certificate (FAR 21.41) includes the type design (FAR 21.31) plus operating limitations, TCDS, and applicable FAR compliance conditions and limitations
• Repair Stations must perform work in accordance with the manufacturers ICA (FAR 43.13a), an aircarrier's manuals (FAR 145.2) or other FAA approved data.
• Maintenance may be conducted using other methods, techniques and practices acceptable to the Administrator that accomplish the same end result with respect to airworthiness i.e.; conformity to the type design and safe for operation
• Repairs, alterations, or deviations from the Manufacturers ICA which are major require FAA approved data
• Maintenance must return the product to either its original or properly altered configuration (FAR 43.13b)
PERFORMANCE OF MAINTENANCE PERFORMANCE OF MAINTENANCE AND ALTERATIONAND ALTERATION
• In Closing:
– Don’t confuse compliance with safe nor non-compliance with unsafe
– There is no such thing as an isolated event
FUNDAMENTAL CERTIFICATION CONCEPTSFUNDAMENTAL CERTIFICATION CONCEPTSENGINES AND APU’SENGINES AND APU’S
POWERPLANT INSTALLATIONSPOWERPLANT INSTALLATIONS
Kathrine RaskSenior Engineer, Propulsion Branch
Seattle Aircraft Certification Office
PROPULSION SYSTEMPROPULSION SYSTEM
• Overview– System Definitions
– Fundamental Certification Concepts
– Fuel Systems
– Engine Ice Protection
– Thrust Reverser
– Engine Operating Characteristics
– Fire Protection
– Uncontained Engine Failure
– Powerplant Instruments
SYSTEM DEFINITIONSSYSTEM DEFINITIONS
• Multi-Engine Installation– Engines are Part 33 certified
Objective is “stand alone” type certificate; generally not airframe specific
• Auxiliary Power Unit (APU) Installation– APU’s qualified to technical standard order
Also “stand alone” certification objective
• Fuel System – Tanks, pumps, plumbing, wiring, etc.
§§ 25.901(a), 25.903
FUNDAMENTAL CERTIFICATION FUNDAMENTAL CERTIFICATION CONCEPTSCONCEPTS
• No Single Failure or Probable Combination of Failures will Jeopardize Safe Operation– A single failure is assumed without
consideration as to its probability of failing– If a failure event cannot be readily detected, it
is counted as a latent existing failure in addition to the first failure
– “Probable” - expected or foreseeable Term often confused with 25.1309
terminology; quantitatively means “not extremely improbable”
§ 25.901(c)
FUNDAMENTAL CERTIFICATION FUNDAMENTAL CERTIFICATION CONCEPTSCONCEPTS
– “Jeopardize safe operation” Continued safe flight and landing from brake
release through ground deceleration to stop Safe flight is determined by both qualitative
and quantitative analysis Consider service experience of similar failures
§ 25.901(c)
FUNDAMENTAL CERTIFICATION FUNDAMENTAL CERTIFICATION CONCEPTS CONCEPTS
• No Single Failure or Probable Combination of Failures will Jeopardize Safe Operation– Accomplished By
Isolation Independence Redundancy Reliability
– Four Exceptions To Rule Uncontained Engine Failures Combustor Case Burn Through Propeller Failure Certain Structural Failures
§§ 25.901(c), 25.903(b), 25.903(d)(1), 25.905(d)
FUEL SYSTEMSFUEL SYSTEMS
• Fuel System Independence/Redundancy• Fuel Flow
– Normal operation– Hot/cold weather, negative “G,” gravity feed
• Lightning Protection• Crashworthiness• Failure Modes
– Ignition sources/flammability – Function of automated fuel system
§§ 25.943, 25.951-25.1001
FUEL SYSTEMFUEL SYSTEM
• New Outlook on Fuel System Safety– Part 21 Special Federal Aviation Regulation
Retroactive design review of in-service airplanes
– New Part 25 Regulation Changes Improved safety analysis Minimized fuel tank flammability
– Operating Rule Changes Mandate improved maintenance
SFAR No. 88; §§ 25.981, 91.410, 121.370, 125.248, 129.32
ENGINE ICE PROTECTIONENGINE ICE PROTECTION
• Engine Installation Shall Continue to Operate in Severe Environmental Conditions– Review ice accumulations on engine, inlet, and
other airframe surfaces that could be ingested Freezing fog on ground Falling and blowing snow on ground Late activation of ice protection by crew in
flight Fan ice shedding and procedures
– No engine icing limitations Engine power/thrust always required to exit
inadvertent icing conditions
§ 25.1093
THRUST REVERSERTHRUST REVERSER• Demonstrate compatibility with engine
• Demonstrate compatibility with airplane – Significant change in philosophy since the Lauda 767 accident
Exposed vulnerability to certain aircraft during high speed flight
Long Strut/Low Mount Short Strut/High Mount
T/R pattern under wing - no stall T/R pattern over wing - stall
THRUST REVERSERTHRUST REVERSER
• Two Options to Meet Part 25 Safety Intent:– To demonstrate that the airplane must be
controllable under any possible position of the thrust reverser
Thorough flight test controllability demonstration
Demonstrate operable reverser can be restored to the forward thrust position
Minimize potential for in-flight deployment
§ 25.933
THRUST REVERSERTHRUST REVERSER
• Two Options to Meet Part 25 Safety Intent (continued):– To demonstrate the possibility of an inflight
thrust reverser deployment will not occur within the life of the airplane fleet
Rigorous qualitative and quantitative analysis with more conservative assumptions
Typically results in three independent thrust reverser restraints
Review minimum dispatch configurations
THRUST REVERSERTHRUST REVERSER
• Maintenance has played a significant role in the majority of inflight thrust reverser incidents – Review safety analysis assumptions to ensure they
are tolerant to human error– Review general thrust reverser maintenance
procedures– In depth review of thrust reverser lock-out
configuration and procedures
• Vast majority of in-service thrust reverser uncommanded deployments resulted from improperly de-activating system associated with MEL activity
ENGINE OPERATING ENGINE OPERATING CHARACTERISTICSCHARACTERISTICS
• Engines should continue to safely operate throughout the airplane flight envelope
• Engine operation demonstrated at airplane’s limits of :
– Ambient temperature
– Altitude/airspeed/angle of attack
– Tailwind/crosswind
– Rapid and slow power lever movements
– Mechanical/electrical loading
§§ 25.939, 25.931
POWERPLANT FIRE PROTECTIONPOWERPLANT FIRE PROTECTION
• General intent is to provide redundant design: – Minimize potential for fire
Ventilation required to minimize potential of flammable vapor
Managing zone temperatures and sources of ignition
– Minimize effects/duration if a fire should occur Fire walls Quick acting detectors Flammable fluid shut off provisions Drainage provisions Extinguishing
§§ 25.863-25.869, 25.1181-25.1207
UNCONTAINED ENGINE FAILUREUNCONTAINED ENGINE FAILURE
DC-10; 1973
B-747; 2000
UNCONTAINED ENGINE FAILUREUNCONTAINED ENGINE FAILURE
• Uncontained engine failure threat too great to be completely addressed by failsafe philosophy – Some of the threat addressed by prescriptive
requirements Differential compartment loads Damage tolerant structure Decompression
§§ 25.365(e)(1), 25.571(e)(2)-(3), 25.841(a)(3), 25.903(d)(1)
UNCONTAINED ENGINE FAILUREUNCONTAINED ENGINE FAILURE
– Remainder of airplane threat minimized in the event of an uncontained engine or APU failure
Isolation> hydraulic check valves> flammable fluid shut-off provisions & dry bays
Redundancy & Separation> hydraulic line, flight control wires/cables & electric
power> flammable fluid shut-off valves
Shielding> critical structure & systems> auxiliary fuel tanks> APU containment devices
POWERPLANT INSTRUMENTSPOWERPLANT INSTRUMENTS
• Intent is to provide indication of engine parameters, limits, and failures to enable the crew to always maintain control of engine – Limit exceedances (protect rotor integrity)– Fault enunciation - critical failures
Messaging system consistent with flight deck philosophy
Minimize flight crew workload– Pop-up displays– Standby indication – Trend monitoring
§§ 25.1305
OTHER SYSTEM REQUIREMENTSOTHER SYSTEM REQUIREMENTS
– Propeller installation– Oil system– Thrust augmentation– Starting– Component cooling
– Controls– APU– Performance– Powerplant accessories– Inlets/Exhaust
All follow the fundamental concept of fail-safe and isolation
• Part 25 also addresses:
CABIN SAFETYCABIN SAFETYCABIN SAFETYCABIN SAFETY
Frank TiangsingManager, Airframe/Cabin Safety Branch
Transport Airplane Directorate
DEFINITIONDEFINITIONDEFINITIONDEFINITION
• Cabin Safety, the discipline that deals with:– Occupant protection/survival
– Escape from crashes or other emergency events
Mechanical Systems
Cabin Safety Airframe
Electrical Systems
Operations (Flight Standards)
MAIN ELEMENTSMAIN ELEMENTSMAIN ELEMENTSMAIN ELEMENTS
• Occupant protection
• Evacuation
• Fire protection
• Emergency equipment
OCCUPANT PROTECTIONOCCUPANT PROTECTION
• Occupant protection is provided by having:– Seats approved to static and dynamic loads
(§§ 25.561, 25.562, 25.785) – Items of mass retained (§ 25.789)– Padding on projecting objects (§ 25.785(k))– Handholds along aisles (§ 25.785(j))– Slip resistant floors (§ 25.793)– Access to oxygen during a decompression event
(§ 25.1447)
OCCUPANT PROTECTIONOCCUPANT PROTECTION
• Static testing of seats– Seats are tested to loads in the forward, aft,
sideward, up and down directions– Maximum loads from the ground, flight and
emergency landing conditions are applied
OCCUPANT PROTECTIONOCCUPANT PROTECTION
• Dynamic testing of seats – Two test conditions
16g forward load 14g downward load
– Includes occupant injury criteria Head Injury Criteria (HIC) Lumbar load Femur load
– TSO-C127 prescribes minimum performance standards for dynamically tested seats
MAIN ELEMENTSMAIN ELEMENTSMAIN ELEMENTSMAIN ELEMENTS
• Occupant protection
• EVACUATION
• Fire protection
• Emergency equipment
EVACUATIONEVACUATION
Evacuation addresses the means for occupants to safely travel from their seats to the ground or water
EVACUATIONEVACUATION
• Effective evacuation is accomplished by providing: – Appropriate type and number of exits (§ 25.807) – Access to exits (§ 25.813)– Assist means from the aircraft to ground or water
(§ 25.810, TSO C69c)
EVACUATIONEVACUATION
• Effective evacuation is accomplished by providing: – Emergency lighting (§ 25.812)– Emergency evacuation demonstration (§ 25.803, App. J)– Ditching capability (§ 25.801)
MAIN ELEMENTSMAIN ELEMENTSMAIN ELEMENTSMAIN ELEMENTS
• Occupant protection
• Evacuation
• FIRE PROTECTION
• Emergency equipment
FIRE PROTECTIONFIRE PROTECTION
• Interior fire protection is accomplished by addressing the following areas:– Interior materials (§ 25.853, App. F)
Bunsen burner test (Part I) Seat cushion test (Part II) Heat release test (Part IV) Smoke emission test (Part V)
– Cargo compartments (§ 25.855, App. F) Bunsen burner test Oil burner test for Class C compartment liners (Part
III)
FIRE PROTECTIONFIRE PROTECTION
– Lavatories (§§ 25.853(h), 25.854) Waste receptacles
> Must have built-in fire extinguishers> Must be capable of containing fire
Smoke detectors are required – Portable fire extinguishers must be distributed
throughout the aircraft (§ 25.851)
MAIN ELEMENTSMAIN ELEMENTSMAIN ELEMENTSMAIN ELEMENTS
• Occupant protection
• Evacuation
• Fire protection
• EMERGENCY EQUIPMENT
EMERGENCY EQUIPMENTEMERGENCY EQUIPMENT
• Emergency Equipment Required by Part 25 – Fire extinguishers, oxygen bottles, floatation seat
cushions or life vests (§§ 25.851, 25.1415, 25.1447, 121.333(e))
– Overwater operation: life rafts, life vests, survival kits, emergency transmitters, life lines (§ 25.1415)
• Emergency Equipment Required by Part 121– Megaphones, first aid kits, smoke hoods, crash ax,
flashlights (§§ 121.309, 121.337, 121.549)
EMERGENCY EQUIPMENTEMERGENCY EQUIPMENT
• Emergency equipment must be: – Readily accessible (§ 25.1411(a))– Reasonably distributed and arranged so that
its location is obvious, well identified and appropriate for its intended use (§§ 25.851(a), 25.1411)
– Protected from inadvertent damage (§25.1411(b))
HUMAN FACTORS IN PART 25HUMAN FACTORS IN PART 25
Steve BoydAirplane & Flight Crew Interface Branch
Transport Airplane Directorate
• Definition (unofficial) - Human Factors, as it applies to aircraft certification:– The application of scientific theory, principles, data
and methods... – about human abilities, limitations, and other
characteristics... – to the establishment of minimum safety-related
design requirements for flight crew interfaces, tasks, and procedures,...
– and then ensuring that those requirements are met,– in order to promote overall system performance and
safety
HUMAN FACTORS IN PART 25HUMAN FACTORS IN PART 25
• We base the requirements on knowledge and/or assumptions about:– The “human” capabilities and limitations of the
people who will fly the airplanes– Their level of training– Their roles and responsibilities– The demands of the mission
• Note: Requirements for items 2 and 3 are contained in the operating rules
UNDERPINNING FOR THE CREW UNDERPINNING FOR THE CREW INTERFACE REQUIREMENTSINTERFACE REQUIREMENTS
PRIMARY HF AREASPRIMARY HF AREAS
• Human factors issues are integrated into the rules in various subparts
• Main areas include:– The controls and displays that the pilots use– The physical geometry of the flight deck– Integrated aspects of the flight crew interfaces– The evaluation of performance and handling
qualities
COMPETING REQUIREMENTSCOMPETING REQUIREMENTS
All controls reachable,
displays readable
Space necessary for controls and
displays
Situation Awareness
Information Overload
Commonality
Additional functionality
16g seats
External vision Short Pilots
Weight. Panel space
Comfortable seats
Tall Pilots
CONTROLS AND DISPLAYSCONTROLS AND DISPLAYS
• Specific controls and displays are called out for certain functions
• Some are based on “assumed” pilot responsibilities
• Some are required to deal with failures– Driven by failure modes and effects– Pilot actions are intended to mitigate the
failure effects
CONTROLS AND DISPLAYSCONTROLS AND DISPLAYS
• Design to support pilot performance and reduce errors in the use of controls/displays– Arrangement - convenient accessibility and use,
no confusion, standardization– Direction of movement - matches the function– Control shape - standardization for certain
controls– Control labeling - except when function is
obvious– Preventing inadvertent activation - location,
guarding– Color coding - standardization for alerts/limits
FLIGHT DISPLAY FLIGHT DISPLAY ARRANGEMENTARRANGEMENT
• The technology and formats change, but….
Airspeed
Heading
Altitude
Attitude
FLIGHT DECK GEOMETRYFLIGHT DECK GEOMETRY
• Accommodate a range of pilot sizes– Short pilots can reach everything they need– Tall pilots can fit in the flight deck
• Pilots can see what they need to see– Installation location of the displays/controls– Windows provide adequate visibility
• Reflections and glare• Emergency egress
INTEGRATION ASPECTS OF THE INTEGRATION ASPECTS OF THE FLIGHT DECKFLIGHT DECK
• Workload– Workload must be acceptable for the minimum
flight crew– No unreasonable concentration or fatigue
• Crew response to failures • Environmental conditions
– Noise and vibration– Lighting
• Intended function - assessed in context
EVALUATION OF PERFORMANCE EVALUATION OF PERFORMANCE AND HANDLING QUALITIESAND HANDLING QUALITIES
• HF considerations are embedded in numerous requirements related to performance and handling qualities. Examples:– ...can be “consistently executed in service by
crews of average skill.”– …may not “require exceptional piloting or
alertness.”– “Reasonably expected variations in service from
the established takeoff procedures… may not result in unsafe flight characteristics…”
• Requirements are based on experience– Human performance “margins” are usually in
guidance material• Test pilots are the key players in evaluating
performance/HQ– Subjective assessment (including consideration of
line pilot capabilities and line operations)– Performance data - measuring airplane
performance with pilots in the loop– Close coordination between Certification and
Flight Standards (Aircraft Evaluation Group) pilots
EVALUATION OF PERFORMANCE EVALUATION OF PERFORMANCE AND HANDLING QUALITIESAND HANDLING QUALITIES