1. FOR TRAINING PURPOSE ONLY
Malaysian Institute of Aviation Technology
AJD 21603 ROTORCRAFT SYSTEM,
MAINTENANCE AND ROLE EQUIPMENT
WEEK 2
HELICOPTER DOORS, WINDOW AND WINDSCREEN.
HELICOPTER SYMMETRY CHECKS

2. FOR TRAINING PURPOSE ONLY
Malaysian Institute of Aviation Technology
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.

3. FOR TRAINING PURPOSE ONLY
Malaysian Institute of Aviation Technology
INTRODUCTION
THE 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.

4. FOR TRAINING PURPOSE ONLY
Malaysian Institute of Aviation Technology
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.

5. FOR TRAINING PURPOSE ONLY
Malaysian Institute of Aviation Technology
COCKPIT DOOR ON AS 355
PICTURE 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)

6. FOR TRAINING PURPOSE ONLY
Malaysian Institute of Aviation Technology
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.

7. FOR TRAINING PURPOSE ONLY
Malaysian Institute of Aviation Technology
EC120

8. FOR TRAINING PURPOSE ONLY
Malaysian Institute of Aviation Technology
TYPICAL INSPECTION ON COCKPIT DOORS
THE 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

9. FOR TRAINING PURPOSE ONLY
Malaysian Institute of Aviation Technology
CABIN DOOR
THE 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 DOOR
2. 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.

10. FOR TRAINING PURPOSE ONLY
Malaysian Institute of Aviation Technology
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.

11. FOR TRAINING PURPOSE ONLY
Malaysian Institute of Aviation Technology
BELL 412 CABIN DOOR

12. FOR TRAINING PURPOSE ONLY
Malaysian Institute of Aviation Technology
SLIDING
DOOR

13. FOR TRAINING PURPOSE ONLY
Malaysian Institute of Aviation Technology
STANDARD DOOR FITTED TO AS 355
PICTURE 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

14. FOR TRAINING PURPOSE ONLY
Malaysian Institute of Aviation Technology
CHARACTERISTICS OF CABIN DOOR
LIKE 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.

15. FOR TRAINING PURPOSE ONLY
Malaysian Institute of Aviation Technology
SLIDING DOOR MECHANISM ON AS355
PICTURE 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.

16. FOR TRAINING PURPOSE ONLY
Malaysian Institute of Aviation Technology
CABIN DOORS EMERGENCY ESCAPE
SIMILAR TO COCKPIT DOOR, EMERENCY ESCAPE FACILITY IS
ALSO INCORPORATED INTO THE CABIN DOOR INSTALLATION.
TWO METHODS ARE USUALLY EMPLOYED;
1. WINDOWS JETTISON
2. 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.

17. FOR TRAINING PURPOSE ONLY
Malaysian Institute of Aviation Technology
EMERGENCY ESCAPE FOR CABIN
PICTURE 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

18. FOR TRAINING PURPOSE ONLY
Malaysian Institute of Aviation Technology
MARKING VISIBLE FROM OUTSIDE OF THE
DOOR

19. FOR TRAINING PURPOSE ONLY
Malaysian Institute of Aviation Technology
MARKING ON EMERGENCY EXIT

20. FOR TRAINING PURPOSE ONLY
Malaysian Institute of Aviation Technology
LITTER DOOR
LITTER 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.

21. FOR TRAINING PURPOSE ONLY
Malaysian Institute of Aviation Technology
MAINTENANCE ON CABIN DOORS
BASICALLY THE MAINTENANCE ACTIVITIES THAT NEED TO BE
PERFORMED OF CABIN DOORS IS VERY MUCH SIMILAR TO THE
COCKPIT DOORS

22. FOR TRAINING PURPOSE ONLY
Malaysian Institute of Aviation Technology
WINDSCREEN INSTALLATION
WINDSCREEN 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.

23. FOR TRAINING PURPOSE ONLY
Malaysian Institute of Aviation Technology
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.

24. FOR TRAINING PURPOSE ONLY
Malaysian Institute of Aviation Technology
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.

25. FOR TRAINING PURPOSE ONLY
Malaysian Institute of Aviation Technology
EXAMPLE OF WINDSCREEN INSTALLATION ON
AS355

26. FOR TRAINING PURPOSE ONLY
Malaysian Institute of Aviation Technology
HELICOPTER SYMMETRICAL CHECK
HELICOPTER 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.

27. FOR TRAINING PURPOSE ONLY
Malaysian Institute of Aviation Technology
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

28. FOR TRAINING PURPOSE ONLY
Malaysian Institute of Aviation Technology
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