AVIATION OCCURRENCE REPORT BRAKE ... Occurrence Report Brake Malfunction Provincial Airlines Ltd....

AVIATION OCCURRENCE REPORT

BRAKE MALFUNCTION

PROVINCIAL AIRLINES LTD.PIPER PA-31-350 NAVAJO CHIEFTAIN C-GWLW

FOX HARBOUR, NEWFOUNDLAND27 JUNE 1994

REPORT NUMBER A94A0124

MANDATE OF THE TSB

The Canadian Transportation Accident Investigation and Safety Board Actprovides the legal framework governing the TSB's activities. Basically, theTSB has a mandate to advance safety in the marine, pipeline, rail, andaviation modes of transportation by:

! conducting independent investigations and, if necessary, publicinquiries into transportation occurrences in order to make findings asto their causes and contributing factors;

! reporting publicly on its investigations and public inquiries and on therelated findings;

! identifying safety deficiencies as evidenced by transportationoccurrences;

! making recommendations designed to eliminate or reduce any suchsafety deficiencies; and

! conducting special studies and special investigations ontransportation safety matters.

It is not the function of the Board to assign fault or determine civil or criminalliability. However, the Board must not refrain from fully reporting on thecauses and contributing factors merely because fault or liability might beinferred from the Board's findings.

INDEPENDENCE

To enable the public to have confidence in the transportation accidentinvestigation process, it is essential that the investigating agency be, and beseen to be, independent and free from any conflicts of interest when itinvestigates accidents, identifies safety deficiencies, and makes safetyrecommendations. Independence is a key feature of the TSB. The Boardreports to Parliament through the President of the Queen's Privy Council forCanada and is separate from other government agencies and departments.Its independence enables it to be fully objective in arriving at its conclusionsand recommendations.

The Transportation Safety Board of Canada (TSB) investigated this occurrence for thepurpose of advancing transportation safety. It is not the function of the Board to assign faultor determine civil or criminal liability.

Aviation Occurrence Report

Brake Malfunction

Provincial Airlines Ltd.Piper PA-31-350 Navajo Chieftain C-GWLWFox Harbour, Newfoundland27 June 1994

Report Number A94A0124

Synopsis

The Piper Navajo Chieftain departed Mary's Harbour en route to Fox Harbour, Newfoundland. Theinitial brake application during the landing roll at Fox Harbour resulted in normal braking action. However, subsequent brake applications resulted in progressively greater brake pedal travel and lessbraking response. The captain took control and ground looped the aircraft rather than overrun therunway and descend a 75-foot rock embankment. The flight crew and the three passengers, alluninjured, evacuated the aircraft and walked to the airport terminal.

The Board determined that brake fluid boiling was the most probable cause of the brake failure. Contributing to this occurrence was the high energy landing in Mary's Harbour, the insufficient brakecooling time between the Mary's Harbour and Fox Harbour landings, the flight crew's brakingtechnique, and the standard brake system installed on the aircraft.

Ce rapport est également disponible en français.

TABLE OF CONTENTS

TRANSPORTATION SAFETY BOARD iii

Table of ContentsPage

1.0 Factual Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.1 History of the Flight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.2 Injuries to Persons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.3 Damage to Aircraft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.4 Other Damage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.5 Personnel Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.6 Aircraft Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

1.7 Meteorological Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

1.8 Aerodrome Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

1.9 Flight Crew Actions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

1.9.1 Control of the Aircraft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

1.9.2 Braking Technique . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

1.10 Wreckage and Impact Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

1.10.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

1.10.2 Brake Examination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

1.11 Brake Design and Braking Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

1.11.1 Brake Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

1.11.2 Brake Lining Conditioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

1.11.3 Brake Heating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

1.12 Brake Kinetic Energy on Landing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

1.12.1 Kinetic Energy Formula . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

1.12.2 Kinetic Energy Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

1.13 Additional Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

1.13.1 Maintenance Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

1.13.2 Flight Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

2.0 Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

2.1 Brake System Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

2.2 Residual Heat and Braking Technique . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

2.3 Brake Linings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

2.4 Flight Crew Actions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

TABLE OF CONTENTS

iv TRANSPORTATION SAFETY BOARD

3.0 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

3.1 Findings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

3.2 Causes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

4.0 Safety Action . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

4.1 Action Taken . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

5.0 AppendicesAppendix A - List of Supporting Reports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Appendix B - Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

List of FiguresFigure 1 - Brake disc . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Figure 2 - Brake assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Figure 3 - Brake assembly on brake disc . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

FACTUAL INFORMATION

TRANSPORTATION SAFETY BOARD 1

1.0 Factual Information

1.1 History of the Flight

The aircraft, a Piper Navajo Chieftain, departedSt. Anthony on a scheduled 28-minute flight toMary's Harbour, Newfoundland, about 66 milesto the north. Nine minutes after landing inMary's Harbour, the aircraft departed for ashort flight to Fox Harbour, eight miles east.

The aircraft touched down on runway05 at Fox Harbour, about 200 feet beyond thethreshold, and the co-pilot, who was the pilotflying (PF)1, applied the brakes. Subsequentbrake applications resulted in progressivelygreater brake pedal travel and less brakingresponse. The captain, who was the pilot notflying (PNF), took control of the aircraft andground looped it, rather than overrun theairstrip and descend a 75-foot rockembankment.

The flight crew and three passengersevacuated the aircraft uninjured.

1 See Glossary for all abbreviations and acronyms.

2 Units are consistent with official manuals, documents,reports, and instructions used by or issued to the crew.

3 All times are NDT (Coordinated Universal Time (UTC)minus 3 1/2 hours) unless otherwise stated.

The accident occurred at latitude52°22'N and longitude 55°41'W, at an elevationof 75 feet above sea level (asl)2, atapproximately 0900 Newfoundland daylighttime (NDT)3 during the hours of daylight.

1.2 Injuries to Persons

Crew Passengers Others Total

Fatal - - - -Serious - - - -Minor/None 2 3 - 5

Total 2 3 - 5

1.3 Damage to Aircraft

The aircraft sustained substantial damageduring the landing event.

1.4 Other Damage

There was no other damage.

1.5 Personnel Information

Pilot-in-command Co-pilot

Age 25 26Pilot Licence ATPL CPLMedical Expiry Date 1 May 95 1 Jan 95Total Flying Hours 4,000 2,500Hours on Type 1,200 1,200Hours Last 90 Days 300 300Hours on Type Last 90 Days 180 300Hours on Duty Prior to Occurrence 2 4Hours off Duty Prior to Work Period 12 38

1.6 Aircraft Information

Manufacturer Piper Aircraft CorporationType and Model PA-31-350 Navajo ChieftainYear of Manufacture 1974Serial Number 317405221Certificate of Airworthiness (Flight Permit) ValidTotal Airframe Time 9,368 hrEngine Type (number of) Lycoming TIO-540-J2BD (2)Propeller/Rotor Type (nubmer of) Hartzell HC-E3YR-2ATF (2)Maximum Allowable Take-off Weight 7,250 lbRecommended Fuel Type(s) 100/130 minimumFuel Type Used 100 LL

The aircraft was certified, equipped andmaintained in accordance with existingregulations and approved procedures.

The aircraft was originally type certifiedfor a maximum take-off and landing weight of

FACTUAL INFORMATION

2 TRANSPORTATION SAFETY BOARD

7,000 pounds. However, an approvedmodification to the aircraft, a vortex generatorkit, increased the maximum take-off weight to7,250 pounds. The modification did notchange the maximum landing weight of 7,000pounds.

The aircraft's maximum allowablelanding weight was exceeded by 125 poundsduring the Mary's Harbour landing. Theaircraft weight and centre of gravity during thelanding at Fox Harbour were within theprescribed limits.

1.7 Meteorological Information

The Mary's Harbour automated weatherobservation system (AWOS) reported weatherat the time of the occurrence was 1,300 feetscattered, visibility five miles in rain showers,and light winds.

The Fox Harbour weather, reported bythe flight crew, was visibility three miles in rainshowers, fog patches, and light and variablewinds.

1.8 Aerodrome Information

The Fox Harbour airport, which is operated bythe Government of Newfoundland, has a2,200-by-75 foot gravel runway. A 100-footsoft gravel surface extends beyond thedeparture end of runway 05, followed by a rockembankment that descends 75 feet.

1.9 Flight Crew Actions

1.9.1 Control of the Aircraft

The PF is responsible for controlling theaircraft. When there is a need to exchangecontrol of the aircraft between pilots, theprocedure that should be followed is for thepilot taking control to call "I have control," andfor the pilot relinquishing control to call "youhave control." This control exchange can beinitiated by either pilot.

Proper verbal transfer of control fromthe PF to the PNF did not take place during the

Fox Harbour landing. However, the PNF, thecaptain, did take control of the aircraft andidentified that he also had no braking action.

The company procedure for anovershoot is for the pilot controlling theaircraft to advance the throttles. During thelanding at Fox Harbour the captain called"overshoot," but did not advance the throttles. The captain then decided he did not havesufficient runway remaining to carry out anovershoot, so he ground looped the aircraftbefore it went past the departure end of therunway and over the embankment.

1.9.2 Braking Technique

The flight crew were using a braking techniqueof brake on-off-on (pumping the brakes) afteraircraft touchdown. An alternative brakingtechnique would have been to apply the brakesafter touchdown and maintain positive brakepressure until the aircraft had come to a stop. The latter technique provides a shorter landingdistance. Also, the brake system, due to ahigher constant brake pressure, could absorbmore heat before the brake fluid would boil.

The flight crew believed that theirbraking technique resulted in less wear andlonger life to the aircraft brake systemcomponents. This technique was an acceptedpractice used by some of the operator's pilots.

The operator did not have a StandardOperating Procedure (SOP) manual for thisaircraft.

1.10 Wreckage and Impact Information

1.10.1 General

The aircraft was substantially damaged duringthe landing event. The ground loop overloadedthe aircraft's left main landing gear downlockand caused it to fail and the gear to collapse. The left engine propeller was damaged when itstruck the ground after the landing gearcollapsed. The left wing panels were visiblywrinkled on the outboard six feet of wing andthe left flap was damaged. The left stabilizer

FACTUAL INFORMATION


and elevator were also damaged, as was thefuselage structure below the main cabin door.

1.10.2 Brake Examination

After the occurrence, the brake system waschecked for damage and proper operation. There was no evidence of brake fluid leaksfrom the brake system components. When thebrakes were applied, the pedal response wasspongy, similar to the response that is felt whenair is in the brake system. When the pedalswere pumped and then held, the pedal pressurewould remain hard.

The aircraft's main wheel brake discsand the wheel brake assemblies, including thebrake linings, brake cylinders, and brake torqueplates, were removed from the aircraft andtransported to the Regional WreckageExamination Facility in Moncton, NewBrunswick. The following observations weremade:

Brake discs: Both brake discs wereconed beyond the manufacturer's .015-inch limit. The left wheel brake discwas coned .139 inches and the rightwheel brake disc was coned .054inches. The left disc was marginallythinner than the right and the left dischad accumulated more landing cyclessince installation. Both brake discthicknesses were within the limitsspecified by the brake manufacturer'sComponent Maintenance Manual (CMM).

Figure 1 -Brake disc

Wheel Brake Cylinders: Both brakecylinders were intact and showed no evidenceof cracks or external leakage.

Brake Linings/Left Brake: All sixbrake linings met and exceeded the minimumthickness requirements specified by the CMM. The steel backing on some of the linings waswarped and bluish in colour.

Pressure Plate/Left Brake: Threebrake linings are attached to the pressure plateand are located on the brake piston side of thebrake disc.

The linings are attached to pins that areriveted to the pressure plate. The pressureplate was warped, all six pins were loose in thepressure plate, and several pins had elongatedtheir respective holes.

Figure 2 - Brake assembly

FACTUAL INFORMATION


Brake Linings/Right Brake: All sixbrake linings had minimal material remaining. Two of the three back plate linings were wornto the point that the retaining pin hole outlineswere visible on the lining face. The CMMstates that the lining is worn beyond limitswhen the holes for the pins are visible on thebrake lining surface.

Figure 3 -Brake assembly on brake disc

The three pressure plate linings were worn tonear minimum thickness limits.

Pressure Plate/Right Brake: The rightbrake pressure plate was warped but the brakelining retaining pins were secure in the plate.

1.11 Brake Design and BrakingResponse

1.11.1 Brake Design

The aircraft's wheel and brake (40-102/30-68series) normal land kinetic energy capacity israted at 700,000 ft-lb. This indicates that it willcomplete35 dynamometer stops at that energy and at adeceleration rate of 10 ft/sec/sec.

One dynamometer stop is consideredequivalent to the kinetic energy that isproduced during one short field landingsequence. Therefore, new brake linings shouldlast for a minimum of 35 landings before liningreplacement is required.

The 30-68A standard brake wasoriginally installed on the Piper Navajo, whichhad a 6,500-pound maximum landing weightwith a speed of about 70 knots in landingconfiguration. The landing weight increased to7,000 pounds with a speed of 74 knots inlanding configuration when the NavajoChieftain was introduced. Although the samebrake was approved for Navajo models, aheavy-duty brake was available for the Chieftainthat was rated to a higher energy capacity.

Although the 30-68 series aircraft brakeis rated at 700,000 ft-lb, it has the capacity tooperate above this brake rating. Nevertheless,when the energy produced is higher than thedesign rating and the brake has not cooledsufficiently to dissipate the stored energy, anyfurther braking can produce brake fade, brakedisc coning, and abnormal brake response.

All brake cylinders incorporateinsulators that provide protection against heattransfer from the brake disc to the brakecylinders.

1.11.2 Brake Lining Conditioning

Brake lining conditioning is a manufacturer'srecommended procedure that should befollowed after new linings are installed on theaircraft. Two consecutive full-stop brakingapplications are performed at a speed of 30 to35 knots to glaze the brake lining material andprovide optimum lining service life. If theconditioning is not done, the lining service lifewill decrease and the brakes will be lesseffective. Also, there will be a corresponding"hard pedal" feel, and a greater-than-normalpedal effort will be required to decelerate theaircraft.

FACTUAL INFORMATION


1.11.3 Brake Heating

If the brake discs are subjected to excessiveheat during a landing, the brake discs can cone. As the disc starts to cone, the running clearancebetween the linings and the disc decreases. Also, the misalignment between the disc andlinings causes the pressure distribution tobecome non-uniform, producing less brakingaction.

Excessive heat energy can be generatedif the brake has not had sufficient time to coolbetween stops. This residual energy is stored inthe disc and is added to the energy createdduring the next stop. The resulting hightemperatures can exceed the brake insulationcapabilities and cause the brake fluid behind thebrake cylinder pistons to boil. Since a gas iscompressible, any continued brake applicationwill produce excessive pedal travel and poor orno brake response.

A brake fluid will reach a highertemperature without boiling when the brakefluid is under pressure. If the fluid is closeenough to its boiling point when underpressure, the fluid will boil when the pressure isremoved.

1.12 Brake Kinetic Energy on Landing

1.12.1 Kinetic Energy Formula

Every brake is designed to a particular brakecapacity measured in ft-lb. The formula forcalculating the kinetic energy (KE) that can beproduced at the brake during a landing event isas follows:

KE = LW x (LS x LS) x .0443 dividedby X, where

KE = Kinetic energy,

LW = aircraft landing weight inpounds,

LS = aircraft landing speed in knots,and

X = The number of brake assemblies peraircraft.

1.12.2 Kinetic Energy Calculations

The following calculations use the aircraft'slanding weights computed from the occurrenceflight load sheets.

Two Mary's Harbour landing speedswere used to highlight the importance oflanding speed in determining the brake kineticenergy. Calculation No. 2 uses the highestlanding speed that the crew feels might havebeen attained.

Mary's Harbour Calculation No. 1

KE = LW x (LS x LS) x .0443 divided by X

= 7125 x 75 x 75 x .0443 divided by 2

= 887,730 ft-lb

Mary's Harbour Calculation No. 2


= 7125 x 85 x 85 x .0443 divided by 2

= 1,140,240 ft-lb

Although the maximum approvedlanding weight was exceeded by 125 pounds,the overweight landing increased the energydeveloped by less than 2 per cent.

Fox Harbour Calculation No. 1


= 6286 x 80 x 80 x .0443 divided by 2

= 891,103 ft-lb

1.13 Additional Information

1.13.1 Maintenance Information

FACTUAL INFORMATION


An Event No. 3 inspection and brake systemrepairs were carried out on the day precedingthe accident. The repairs included replacing allO-rings in both wheel brake assemblies and theparking brake valve.

The operator's Parts and RectificationSheet first identified that 6 of the 12 brakelinings were replaced and then the sheet wascorrected to read 9.

Aircraft Maintenance Record sheetNo. 09916 reads that the pads (brake linings)were worn beyond limits, and the rectificationreads that the pads were replaced. It did notindicate how many pads were replaced.

The Aircraft Maintenance Engineer(AME) did not notice to what extent the leftbrake disc was coned when he replaced the leftbrake linings. However, he was able to tightenthe four bolts and still rotate the tire. Thecaptain helped the AME bleed the brake systemby pumping the brakes from both cockpitpositions.

The brake lining conditioningprocedure was not carried out on theoccurrence aircraft after the linings werereplaced, although the brakes were tested forproper operation.

The flight crew did not experience anyabnormal aircraft brake conditions prior to theFox Harbour landing.

The aircraft records for the previous100 hours of aircraft operation indicated thatbrake lining service life ranged from 80 to 160landings before the linings were replaced.

The aircraft had completed twolandings since the brake work wasaccomplished.

1.13.2 Flight Information

The aircraft departed St. Anthony with 800pounds of fuel on board and an aircraft take-

off weight of 7,240 pounds. The aircraftlanded in Mary's Harbour with 685 pounds offuel on board and an aircraft landing weight of7,125 pounds.

Although the aircraft centre of gravity(C of G) was within limits, the aircraft landingweight in Mary's Harbour exceeded themaximum approved landing weight by 125pounds.

The time interval between thecompletion of the Mary's Harbour arrival taxiphase and the commencement of the departuretaxi phase was nine minutes.

The PF completed the Pilot's OperatingManual checklist that included "Brakes-CheckPressure" prior to the Fox Harbour landing andreported that the brakes were normal.

FACTUAL INFORMATION


ANALYSIS


2.0 Analysis

2.1 Brake System Components

The excessive brake disc coning indicated thatthe discs had experienced higher-than-normaltemperatures. The greater number of landingcycles accumulated by the left brake discprobably contributed to the greater coningobserved on that disc. The extent of discconing present when the brake repairs werecompleted could not be determined. A severelyconed brake disc can cause brake drag,decreased braking efficiency and requiresincreased brake pedal travel to align the brakelinings with the brake disc. The severely coneddiscs were the cause of the spongy pedalcondition.

The AME did not notice to whatextent the left brake disc was coned when hereplaced the left brake linings. However, hewas able to tighten the four bolts and still rotatethe tire.

It is possible that the left brake wasdragging and that the additional heat producedduring the taxi, landing, and take-off phase thatfollowed was responsible for the additionalconing as seen on the left disc. The brake dragwould have been caused by the reducedrunning clearance between the coned left brakedisc and the new brake linings. There was nobrake drag on the right brake because the rightbrake linings had not been replaced.

It is possible that the left brake dragwas great enough to produce additional heat,without a noticeable aircraft yaw to the leftduring ground operations.

The flight crew did not experience anyabnormal brake conditions before the FoxHarbour landing.

The brake pedal response during anexamination following the occurrence indicatedthat there were no internal or external leaks inthe brake system.

2.2 Residual Heat and BrakingTechnique

The brake piston insulators protect the brakecylinders from heat that is generated on the discduring aircraft braking action. The excessivelyconed discs, the warped brake pressure plate,and the warped and discoloured brake liningbackings indicate that these components weresubjected to excessive heat.

When the brake disc is unable to absorbany more heat and the cylinder insulator's heatcapacity is exceeded, the brake cylindertemperature can increase due to heat transferfrom the brake disc and cause the brake fluidbehind the cylinder pistons to boil.

The heat produced when the brakeswere applied during the Fox Harbour landing,combined with the residual heat from theprevious landing, resulted in the brake systemcomponents becoming excessively hot. If thebrake fluid was close to the boiling point whenit was under pressure during brake application,then the decrease in pressure when the co-pilotreleased the brakes using the on-off-on brakingtechnique could have resulted in the fluidboiling.

Once the brake fluid boils, the nextbrake application will produce an increasedbrake pedal travel and decreased brakeresponse.

Had the PF maintained brakeapplication rather than use the on-off-onbraking technique, the increased brake pressuremight have prevented the brake fluid fromreaching the boiling point.

2.3 Brake Linings

The aircraft records indicated that 9 of the 12brake linings were replaced on the previous day. Since the linings are capable of producing aminimum of 35 normal brake energy stopsbefore the lining minimum thickness limits areexceeded, it can be concluded that 9 of the 12linings would indicate minimal wear after onlytwo landings.

ANALYSIS


Since the six right brake liningsexhibited much greater wear than the left brakelinings, it is probable that only the six left brakelinings were replaced during the brakemaintenance and not the nine brake linings asidentified by the Parts and Rectification sheet. It could not be determined what the right brakelining condition was when the maintenance wascarried out.

The left brake pressure plate loose pincondition most probably was present during thebrake work as there were no impact marksaround the pins to indicate that the conditionwas a result of the landing event. Thiscondition could have produced a slight brakelining movement or shift when the brakes werefirst applied.

The complete failure of both brakes,however, could not be attributed to the wornlinings on the right brake or the left brakepressure plate loose pin condition.

2.4 Flight Crew Actions

The captain's action of ground looping theaircraft reduced the risk of extensive damage tothe aircraft and serious injury to the occupants. Had the aircraft descended the rockembankment, there would have been a risk ofwing fuel tank rupture and post-crash fire.

CONCLUSIONS


3.0 Conclusions

3.1 Findings

1. The aircraft was certified, equipped,and maintained in accordance withexisting regulations.

2. There was no brake system abnormalityreported by the pilots prior to the FoxHarbour landing.

3. A standard brake system was installedon the aircraft.

4. The brake components exhibitedevidence that high brake temperatureshad been reached.

5. The brake discs were coned beyond themaximum acceptable limits.

6. Some brake linings did not meet theminimum thickness limits set out in theComponent Maintenance Manual.

7. It is probable that the brake fluidboiled during the Fox Harbour landing.

8. The flight crew's on-off-on brakingtechnique may not have been the mostappropriate method for a short fieldlanding.

9. The time interval between the Mary'sHarbour and Fox Harbour landingswas too short to allow the brake discsto cool sufficiently.

10. There was insufficient runway availablefor the flight crew to initiate a go-around after the brakes had failed.

11. The captain's decision to ground loopthe aircraft reduced the risk ofextensive damage to the aircraft andserious injury to the occupants.

12. The flight crew and passengersevacuated the aircraft withoutdifficulty.

13. The operator does not have a SOPmanual for the PA 31-350, nor is itrequired to by existing legislation.

3.2 Causes

Brake fluid boiling was the most probable causeof the brake failure. Contributing to thisoccurrence was the high energy landing inMary's Harbour, the insufficient brake coolingtime between the Mary's Harbour and FoxHarbour landings, the flight crew's brakingtechnique, and the standard brake systeminstalled on the aircraft.

SAFETY ACTION


4.0 Safety Action

4.1 Action Taken

The operator has since equipped its PiperNavajo aircraft that operate into short airstripswith dual caliper heavy duty brake systems.

This report concludes the Transportation Safety Board'sinvestigation into this occurrence. Consequently, the Board,consisting of Chairperson John W. Stants, and membersZita Brunet and Hugh MacNeil, authorized the release ofthis report on 10 May 1995.

APPENDICES


Appendix A - List of Supporting Reports

The following TSB Engineering Branch Laboratory Report was completed:

LP 144/94 - Brake Lining Deterioration.

This report is available upon request from the Transportation Safety Board of Canada.

APPENDICES


Appendix B - Glossary

AME aircraft maintenance engineerasl above sea levelATPL Airline Transport Pilot LicenceAWOS automated weather observation systemC of G centre of gravityCMM component maintenance manualCPL Commercial Pilot Licencehr hour(s)KE kinetic energy (in foot-pounds)lb pound(s)LS aircraft landing speed (in knots)LW aircraft landing weight (in pounds)NDT Newfoundland daylight timePF pilot flyingPNF pilot not flyingSOP standard operating procedureTSB Transportation Safety Board of CanadaUTC Coordinated Universal Time

TSB OFFICES

HEAD OFFICE

HULL, QUEBEC*Place du Centre4th Floor200 Promenade du PortageHull, QuebecK1A 1K8Phone (819) 994-3741Facsimile (819) 997-2239

ENGINEERINGEngineering Laboratory1901 Research RoadGloucester, OntarioK1A 1K8Phone (613) 998-823024 Hours (613) 998-3425Facsimile (613) 998-5572

*Services available in both officiallanguages

REGIONAL OFFICES

ST. JOHN'S, NEWFOUNDLANDMarineCentre Baine Johnston10 Place Fort William1st FloorSt. John's, NewfoundlandA1C 1K4Phone (709) 772-4008Facsimile (709) 772-5806

GREATER HALIFAX, NOVA SCOTIA*MarineMetropolitain Place11th Floor99 Wyse RoadDartmouth, Nova ScotiaB3A 4S5Phone (902) 426-234824 Hours (902) 426-8043Facsimile (902) 426-5143

MONCTON, NEW BRUNSWICKPipeline, Rail and Air310 Baig BoulevardMoncton, New BrunswickE1E 1C8Phone (506) 851-714124 Hours (506) 851-7381Facsimile (506) 851-7467

GREATER MONTREAL, QUEBEC*Pipeline, Rail and Air185 Dorval AvenueSuite 403Dorval, QuebecH9S 5J9Phone (514) 633-324624 Hours (514) 633-3246Facsimile (514) 633-2944

GREATER QUÉBEC, QUEBEC*Marine, Pipeline and Rail1091 Chemin St. LouisRoom 100Sillery, QuebecG1S 1E2Phone (418) 648-357624 Hours (418) 648-3576Facsimile (418) 648-3656

GREATER TORONTO, ONTARIOMarine, Pipeline, Rail and Air23 East Wilmot StreetRichmond Hill, OntarioL4B 1A3Phone (905) 771-767624 Hours (905)771-7676Facsimile (905) 771-7709

PETROLIA, ONTARIOPipeline and Rail4495 Petrolia StreetP.O. Box 1599Petrolia, OntarioN0N 1R0Phone (519) 882-3703Facsimile (519) 882-3705

WINNIPEG, MANITOBAPipeline, Rail and Air335 - 550 Century StreetWinnipeg, ManitobaR3H 0Y1Phone (204) 983-599124 Hours (204)983-5548Facsimile (204) 983-8026

EDMONTON, ALBERTAPipeline, Rail and Air17803 - 106 A AvenueEdmonton, AlbertaT5S 1V8Phone (403) 495-386524 Hours (403)495-3999Facsimile (403) 495-2079

CALGARY, ALBERTAPipeline and RailSam Livingstone Building510 - 12th Avenue SWRoom 210, P.O. Box 222Calgary, AlbertaT2R 0X5Phone (403) 299-391124 Hours (403)299-3912Facsimile (403) 299-3913

GREATER VANCOUVER, BRITISHCOLUMBIAMarine, Pipeline, Rail and Air4 - 3071 Number Five RoadRichmond, British ColumbiaV6X 2T4Phone (604) 666-582624 Hours (604)666-5826Facsimile (604) 666-7230

AVIATION OCCURRENCE REPORT BRAKE ... Occurrence Report Brake Malfunction Provincial Airlines Ltd....

Documents

Transcript of AVIATION OCCURRENCE REPORT BRAKE ... Occurrence Report Brake Malfunction Provincial Airlines Ltd....