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AJD 21603 ROTORCRAFT SYSTEM, MAINTENANCE AND ROLE EQUIPMENT

WEEK 2

HELICOPTER DOORS, WINDOW AND WINDSCREEN.

HELICOPTER SYMMETRY CHECKS

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LESSON OBJECTIVES AND OUTCOMES

OBJECTIVES:1. GAIN KNOWLEDGE ON METHOD OF CONTRUCTION AND

INSTALLATION OF HELICOPTER DOORS, WINDOWS AND WINDSCREEN.

2. GAIN KNOWLEDGE ON TYPE OF HELICOPTER SYMMETRICAL CHECKS.

OUTCOMES:1. DESCRIBE THE VARIOUS METHODS OF CONSTRUCTION

AND INSTALLATIONOF HELICOPTER DOORS, WINDOWS AND WINDSCREEN.

2. DESCRIBE HOW TO PERFORM AIRFRAME SYMMETRY CHECK AND TRANSMISSION COMPONENTS’ ALIGNMENT CHECK.

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INTRODUCTIONTHE CONSTRUCION OF DOORS FOR BOTH THE COCKPIT AND CABIN COMPARTMENT IS NORMALLY SIMPLE AS THERE IS NO PRESSURISATION INVOLVED.

THE DOOR FOR COCKPIT IS USUALLY OPEN OUTWARDS ON EXTERNAL PIN OR PIANO TYPE HINGES.

THERE IS A SINGLE CATCH THAT IS OPERATED BY A HANDLE INSIDE AND OUTSIDE THE AIRCRAFT.

NORMALLY, A MEANS OF JESTTISON MECHANISM IS INCORPORATED INTO THE DOOR ASSEMBLY AS A MEANS OF OPENING THE DOOR IN AN EMERGENCY.

ON BASIC HELICOPTER THE COCKPIT DOOR IS NORMALLY ‘PLAIN’ MEANS THAT THERE ARE NO COVERED PANEL TO ENHANCE THEIR BEAUTY.

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EXAMPLE OF BELL 412 COCKPIT DOORS

PICTURE ON THE LH SIDE IS AN EXAMPLE OF COCKPIT DOORS FITTED TO BELL412 SERIES OF HELICOPTER.NOTED THAT THE SIMPLICITY IN THE CONSTRUCTION OF THE DOOR ASSEMBLY WHICH MAKES THE REPAIR ACTIVITY MUCH SIMPLER.ON VIP AIRCRAFT HOWEVER, THE DOOR MAY BE FITTED WITH DECORATIVE TRIM TO MAKE THE DOOR MORE BEAUTIFUL.

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COCKPIT DOOR ON AS 355PICTURE ON THE LH SIDE SHOWS THE TYPICAL DOOR FITTED TO THE COCKPIT WHICH INCORPORATED THE JETTISON MECHANISM.

INDICATION IN THE COCKPIT VIA CENTRALISED WARNING PANEL OR CWP IS AVAILABLE TO INDICATE WHETHERTHE STATUS OF DOOR’S LOCKING CONDITION. (EITHER THE DOOR IS LOCKED OR NOT)

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EXAMPLE OF COCKPIT DOOR JETTISON MECHANISM

PICTURE ON THE LH SIDE SHOWS THE JETTISON MECHANISM FITTED TO BELL 412 SERIES HELICOPTER.

IN THE EVENT OF EMERGENCY, THE HANDLE IS PULLED TO RELEASE THE DOOR ASSEMBLY.

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EC120

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TYPICAL INSPECTION ON COCKPIT DOORSTHE ACTUAL INSPECTION REQUIREMENT WILL BE STATED IN THE AIRCRAFT MAINTENANCE SCHEDULE WHICH SHOULD BE ADHERED TO AT ALL TIMES.GENERALLY, THE DOORS ARE INSPECTED DURING THE PRE-FLIGHT, POST FLIGHT AND AT SPECIFIC INSPECTION PERIOD.THE INSPECTION WILL USUALLY COVERS THE PHYSICAL INSPECTION FOR ANY ABNORMALITIES AS WELL AS FUNCTIONAL CHECK.

IT SHOULD BE NOTED THAT JETTISON MECHANISM MUST BE INSPECTED AT INTERVALS SPECIFIED IN THE MAINTENANCE SCHEDULE.

THERE ARE USUALLY CHECK BY MEANS OF SPRING BALANCE TO FIND OUT THE EXACT LOAD TO OPERATE THE JETTISON HANDLE. THE LOAD MUST BE WITHIN THE LIMITS SPECIFIED IN M.M

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CABIN DOORTHE TYPE OF CABIN DOORS FITTED IS NORMALLY RELATED TO THE ROLE(S) THE HELICOPTER IS INTENDED TO BE USED.

THERE ARE NORMALLY 2 TYPES OF CABIN DOOR FITTED TO HELICOPTER;1. SLIDING DOOR2. NORMAL DOOR

SLIDING DOOR IS NORMALLY USED FOR HELICOPTERS THAT INVOLVED IN LAW ENFORCEMENT AGENCY SUCH AS POLICE, SEARCH AND RESCUE AND AIR AMBULANCE.

STANDARD DOOR HOWEVER WILL BE USED FOR HELICOPTER THAT INVOLVED IN NORMAL DAY FLYING SUCH AS VIP AIRCRAFT AND PERSONNEL TRANSPORTATION.

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SLIDING DOOR

PICTURE ON THE LH SIDE SHOWS A TYPICAL PASSENGER DOOR FITTED TO BELL 412 HELICOPTER.IT IS THE SLIDING DOOR TYPE AND ONE OF THE MAIN ADVANTAGE OF THIS TYPE OF DOOR IS THAT IT HAS LARGE OPENINGS WHICH ALLOWS THE HELICOPTER TO PERFORM VARIETY OF ROLES.

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BELL 412 CABIN DOOR

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SLIDING DOOR

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STANDARD DOOR FITTED TO AS 355PICTURE ON THE LEFT SHOWS THE STANDARD DOOR FITTED TO THE AS 355. THE CONSTRUCTION AND ATTACHMENT MECHANISM IS MUCH SIMPLER THAN THOSE OF THE SLIDING DOOR.THE DRAWBACK OF THIS TYPE OF DOOR IS THE LIMITED ACCESS TO THE CABIN HENCE MAKING IT UNSUITABLE FOR CERTAIN TYPE OF OPERATION

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CHARACTERISTICS OF CABIN DOORLIKE THE COCKPIT DOOR CONSTRUCTION OF CABIN DOOR IS ALSO SIMPLE BECAUSE NO PRESSURISATION ELEMENT IS INVOLVED.THE OPERATING MECHANISM FOR SLIDING DOOR TEND TO MORE COMPLICATED THAN THOSE OF THE STANDARD DOOR BECAUSE OF COMPLEX MOVEMENT INVOLVED.THE CONSTRUCTION MATERIAL IS NORMALLY ALUMINIUM ALLOYS BUT THE LATEST GENERATION HAS BEEN MOVING TOWARDS UTILIZING THE COMPOSITE MATERIALS SUCH AS S76.

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SLIDING DOOR MECHANISM ON AS355PICTURE ON THE LH SIDE SHOWS PART OF THE SLIDING DOOR MECAHNISM FITTED TO AS 355.

MORE COMPONENTS ARE NEEDED BECAUSE OF THE COMPLEX MOVEMENT OF THE DOOR.

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CABIN DOORS EMERGENCY ESCAPESIMILAR TO COCKPIT DOOR, EMERENCY ESCAPE FACILITY IS ALSO INCORPORATED INTO THE CABIN DOOR INSTALLATION.

TWO METHODS ARE USUALLY EMPLOYED;1. WINDOWS JETTISON2. WHOLE DOOR JETTISON

WHOLE DOOR JETTISON IS VERY MUCH SIMILAR TO THE COCKPIT DOOR JETTISON. THEY ARE OPERATED BY MEANS ON A HANDLE WHICH RELEASE THE DOOR RETAINING MACHANISM.

WINDOWS JETTISON IS BY MEANS RELEASING THE WINDOWS FROM THE DOOR THE PASSENGERS WILL EXIT THE CABIN THROUGH THE CABIN IN THE EVENT OF EMERGENCY.

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EMERGENCY ESCAPE FOR CABINPICTURE ON THE LH SIDE SHOWS THE MARKING LOCATED ON BOTH THE INSIDE & OUTSIDE OF CABIN WHICH GIVES INSTRUCTION OF HOW TO OPERATE THE WINDOW JETTISON.IT IS NORMALLY BE DONE BY PULLING THE RETAINING SEALS & ONCE PULLED WILL RELEASE THE WINDOWS FROM THE DOOR

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MARKING VISIBLE FROM OUTSIDE OF THE DOOR

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MARKING ON EMERGENCY EXIT

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LITTER DOORLITTER DOOR IS FITTED FOR HELICOPTER THAT IS INTENDED TO BE USED AS AIR AMBULANCE.

EXAMPLE SHOWN IS OF BELL 430.

LITTER DOOR ALLOWS MORE OPENING TO THE CABIN SIMILAR TO THE

SLIDING DOOR.

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MAINTENANCE ON CABIN DOORSBASICALLY THE MAINTENANCE ACTIVITIES THAT NEED TO BE PERFORMED OF CABIN DOORS IS VERY MUCH SIMILAR TO THE COCKPIT DOORS

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WINDSCREEN INSTALLATIONWINDSCREEN INSTALLATION ON HELICOPTER IS SIMILAR TO THOSE OF SMALL FIXED WING AIRCRAFT.EXCEPT FOR THOSE AIRCRAFT WHICH HAS THE FACILITY OF WINDSCREEN HEATING SYSTEM, THE NORMAL INSTALLATION WOULD BE VERY MUCH STRAIGHT FORWARD.PROPER INSTALLATION OF WINDSCREEN IS VERY IMPORTANT AS IMPROPERLY INSTALLED WINDSCREEN CAN RESULT IN DAMAGING THE ASSEMBLY.

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PRECAUTIONS TO BE TAKEN DURING WINDSCREEN INSTALLATION

REFERENCE SHULD ALWAYS BE MADE TO MAINTENANCE MANUAL.

THERE SHOULD BE PROPER SEALING OF MATING SURFACE TO ENSURE NO WATER LEAKAGE.

ONLY ON-MAGNETIC SCREWS BE USED TO ENSURE NON-DISTURBANCE TO MAGNETIC INSTRUMENT EQUIPMENT.

THE SCREWS SECURING THE WINDSCREEN MUST BE TORQUE-LOADED TO SPECIFIC VALUES SPECIFIED IN M.M. FAILURE TO DO SO CAN DAMAGE THE WINDSCREEN.

FOR WINDCREEN EQUIPPED WITH THE HEATING SYSTEM, FUNCTIONAL CHECK MUST BE CARRIED OUT IAW M.M. CARE TO BE TAKEN TO PREVENT OVERHEAT DURING TESTING.

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WINDSCREEN INSPECTION

INSPECTION ON WINDSCREEN WILL BE SPECIFIED IN MAINTENANCE SCHEDULE.

GENERALLY IT WILL INVOLVES VISUAL CHECK TO ENSURE NO EXCESSIVE CRAZING ON THE WINDSCREEN.

THE WINDSCREEN HEATING SYSTEM MIGHT ALSO BE SUBJECTED TO INSPECTION AT SPECIFIC INTERVALS.

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EXAMPLE OF WINDSCREEN INSTALLATION ON AS355

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HELICOPTER SYMMETRICAL CHECKHELICOPTER SYMMETRICAL CHECK IS NORMALLY PERFORMED AT INTERVALS SPECIFIED IN THE MAINTENANCE MAUNUAL OR WHENEVER THE INTERGRITY OF THE FUSELAGE IS IN DOUBT. FOR EXAMPLE AFTER THE HEAVY LANDING INCIDENT, THE SYMMETRICAL CHEK IS PERFORMED TO ENSURE THAT THE FUSELAGE AND ALL ITS ASSOCIATED COMPONENTS SUCH AS TAIL BOOM AND STABILIZERS ARE STILL WITHIN THE DIMENTIONAL LIMITS STATED IN THE MAINTENANCE MANUAL.

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The alignment or symmetry check is made after the helicopter has been leveled.

This check is made by measuring the distance between certain points on the helicopter.

These points are selected because they are relatively static and because their location will best reflect any misalignment.

Most  manufacturers recommend that the measurements be taken directly from one  specified  point  to  another.  

On  other  types  of  aircraft,  drop  points  are provided at various locations for use in checking the alignment.

Plumb bobs  are  dropped  from  each  of these points to the reference plane (floor) so that the pattern for measurement may be described.

TYPICAL PROCEDURES

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When you are using this method, the elevation check dimensions are measured from the drop points to  the reference plane; in this case, the floor.

The  horizontal check dimensions are measured from one point (described by the plumb bob), along the reference plane (floor), to another point.

If the alignment check measurements exceed the tolerances listed in the aircraft structural repair manual, the aircraft must be considered non-airworthy until a special disposition an be made by higher  authority