ALL OPERATORS TELEX - ALL OPERATORS TELEX 

TO: A320 FAMILY OPERATORS 

SUBJECT: ATA32 MAIN LANDING GEAR (MLG) DOOR ACTUATOR INTERNAL BREAKAGE 

OUR REF: AOT A320-32A1390 DATED 10 February 2011 

1. AIRCRAFT AFFECTED: 

All A318/A319/A320/A321 aircraft (A/C). 

2. REFERENCED DOCUMENTATION : 

- Ref. - Ref. - Ref. - Ref. - Ref. - Ref. - Ref . - Ref. - Ref. - Ref. - Ref. - Ref. - Ref. - Ref. 

1: CMM 32-31-35, Figure 2, item 80 Damping Housing 2: CMM 32-31-35, Figure 2, item 130 Spiroloc Ring 

3: CMM 32-31-35, Figure 2, item 140 Dampin~ Rin~ 

4: CMM 32-31-35, Figure 2, item 150 Retain1ng R1ng 5: MOD 38274 I Airbus SB 32-1338 dated of Jul 22/08 

6: GE Aviation VSB 200- 32-528 

7: EUAD 2006-0112R1 

8: Airbus SB 32-1309R2 dated of sep 24/09 

9: TSM 32-31-00-810-857 "MLG Door (LH) does not open f ully" 10: TSM 32-31-00-810-858 "MLG Door (RH) does not open fully" 11: TSM 32-31-00-810-860 "MLG door (LH) does not close fully" 12: TSM 32-31-00-810- 861 "MLG door (RH) does not close fully" 13: FOT 999.0008/11 dated of 03 February, 2011 

14: OEB 209/1 

3. REASONS: 

The purpose of this AOT is to advise A320 Family operators of recent cases 

of MLG Door Actuator PN 114122012 (post-Ref. 5) internal damage and to 

recommend operators to perform a weekly check of specific centralized Fault 

Display System (CFDS) messages (refer to Para 4.2.1) and the repetitive door opening inspection (refer to Para 4.2.2). 

3.1 FACTS: 

Further to i ntroduction of door actuators PN 114122012(Post-Ref. 5 

standard) in Jul 2008, seven operators have recently experienced Post-Ref. 

5 MLG Door Actuator failures. 

The door actuator failures have been identified during maintenance ground door opening (by gravity) or following CFDS messages found on Post Flight Report (PFR). 

Maintenance reported the involved MLG Doors were difficult to manually open and confirmed the MLG Door Actuator being at the origin of the slow door 

operation. 

For most occurrences, CFDS messages were present on previous leg reports. 

3.2 CONSEQUENCES: 

Ultimately, the internal parts failure may result in the Actuator Rod to 

extend slowly delaying t he MLG Door operation or stopping just before the 

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end of stroke preventing t he door to reach the fully open position. This excessive actuator stiffness could potentially impair the free-fall 

extension when Doors and MLG are extended by gravity. 

3.3 AIM: 

The aim of this AOT is to recommend operators to perform on all door 

actuators pre and post MOD 38274/SB A320-32-1338 (Ref. 5) the following inspections: 

-weekly check of specific CFDS Messages (listed i n Para 4.2.1), 

-Repetitive inspection of the MLG door actuator for restricted 

extension using the Ground Door Opening Handle. 

This AOT supersedes the Airbus ISB A320-32-1309 (Ref. 8). 

3.4 INVESTIGATION: 

Initial investigation of failed actuators PN 114122012 (Post Ref. 5) internal part damage. Damping ring (Ref. 3), retaining ring (Ref. 4) spiroloc ring (Ref. 2) were found in multiple pieces. The damping housing (Ref. 1) showed extensive damage on its internal 

diameter (ID). 

showed 

and 

The disassembly has highlighted that the same i nternal parts are failing on 

the Pre-Ref. 5 and Post-Ref. 5 actuators. 

Identification of the root cause is under investigation. 

In parallel, a sampling of in service Post-Ref. 5 standard actuators PN 

114122012 has been launched by Airbus to aid the failure root cause 

analysis. 

4. SHORT-TERM ACTIONS: 

4.1 PLANNING AND MANPOWER: 

4.1.1 ACCOMPLISHMENT TIMESCALE : 

-The accomplishment of the weekly CFDS messages check mentioned in 

Para 4.2.1 must be performed no later than two (2) weeks from receipt of this AOT. For all aircraft, repeat the CFDS messages check every week. 

-The accomplishment of the MLG door actuator inspection mentioned in 

Para 4.2.2 must be performed no later than 800 FC from receipt of 

this AOT. For all aircraft, repeat the MLG door actuators inspection 

at i ntervals not exceeding 425FC. 

4.2 DESCRIPTION: 

4.2.1 CFDS MESSAGES CHECK: 

A slow door operation (during opening or closure) could lead to the 

following CFDS messages being triggered by both LGCIU (by pair) for the 

same MLG door. Airbus recommends A320 Family operators to perform a weekly check of the following CFDS messages: 

For slow door opening of the RH MLG door: 

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- "323173 R L/G DOOR OPEN PROX SNSR 32GA TGT POS" (from LGCIU1) 

AND - "323173 R L/G DOOR OPEN PROX SNSR 34GA TGT POS" (from LGCIU2) 

For slow door opening of the LH MLG door : 

- "323173 L L/G DOOR OPEN PROX SNSR 33GA TGT POS" (from LGCIU1) AND - "323173 L L/G DOOR OPEN PROX SNSR 35GA TGT POS" (from LGCIU2) 

For slow door closure of the RH MLG door: 

- "323173 R L/G DOOR CLOSED PROX SNSR 26GA TGT POS" (from LGCIU1) 

AND - "323173 R L/G DOOR CLOSED PROX SNSR 28GA TGT POS" (from LGCIU2) 

For slow door closure of the LH MLG door : 

- "323173 L L/G DOOR CLOSED PROX SNSR 27GA TGT POS" (from LGCIU1) 

AND - "323173 L L/G DOOR CLOSED PROX SNSR 29GA TGT POS" (from LGCIU2) 

If a pair of above CFDS messages (from LGCIU1 & LGCIU2)are found on the PFR 

for the same flight, the door actuator inspection mentioned in Para 4.2.2 

of this AOT must be performed prior to the next flight to ensure smooth 

operation of the door actuator. 

If the movement of the door actuator i s found to be restricted (stiff 

action or reduced stroke) during the inspection mentioned in Para 4 . 2.2, 

the affected MLG door actuator must be replaced prior to the next flight. For further trouble shooting recommendations, refer to the associated TSM 

tasks Ref. 9, 10, 11 and 12. 

NOTE: The above menti oned TSM tasks will be revised to recommend door 

actuator inspection as per Para 4.2.2 of this AOT. The revision of TSM 

Tasks Ref. 9, 10 , 11 and 12 is targeted for end of March 2011. 

4 . 2. 2 DOOR ACTUATOR I NSPECTION : 

Accomplish the followi ng repetitive inspection every 425 FC : 

MANPOWER : 

For actuator inspection: 

Total manhours:1 .5 

Elapsed time (hours):1.0 

GENERAL: 

WARNING: MAKE SURE THAT THE SAFETY DEVICES AND THE WARNING NOTICES ARE 

IN POSITION BEFORE YOU START A TASK ON OR NEAR: - THE FLIGHT CONTROLS - THE FLIGHT CONTROL SURFACES - THE LANDING GEAR AND THE RELATED DOORS - COMPONENTS THAT MOVE . MOVEMENT OF COMPONENTS CAN KILL OR INJURE PERSONS. 

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WARNING: MAKE SURE THAT THE GROUND SAFETY-LOCKS ARE CORRECTLY INSTALLED ON 

THE LANDING GEAR. 

THIS PREVENTS UNWANTED MOVEMENT OF THE LANDING GEAR. 

WARNING: MAKE SURE THAT YOU OBEY ALL THE WARNINGS AND THE CAUTIONS INCLUDED 

IN THE REFERENCED PROCEDURES. 

NOTE:The procedure that follows is applicable to the LH and RH MLG 

doors. 

INSPECTION: 

(a)Manually open the LH MLG door by using the door opening controlhandle as per AMM 32-12-00 page block 201, and make sure that: 

-The door.opens ~y gravity alone to at least the point at which the 

actuator 1s vert1cal 

-The movement of the door is smooth and continuous (there are no 

sudden changes of velocity) 

-The door should open from fully closed position to the point at 

which the door actuator is vertical either at, or before, 30 

seconds. Timing is to start at the point of i nitial LG door 

movement away from the "closed" position. 

(b)If the door has not fully opened make sure that: 

-The door can be easily pushed to the fully open position with 

just one hand 

-The resistance to motion is smooth (hydraulic resistance only) 

(c)With the door fully open, measure the dimension 'DIM' shown in the 

attached appendix A diagram. 

-Dimension DIM must be >385mm 

(d) Move the door by hand away from the fully open position for approx 30 

degrees and back to the fully open position, to make sure that: 

-The resistance to motion is smooth (hydraulic resistance only) 

(e) The LH MLG door actuator must be replaced if any of the checks in 

steps (a) to (d) fail 

(f) Repeat the work steps (a) to (e) for the RH MLG door 

REPAIR: 

(a) Replacement of the MLG door actuator. 

-Remove the MLG door actuator as per AMM 32-31-35, Page block 401. 

-Install the MLG door actuator as per AMM 32-31-35, Page block 

401. 

NOTE: The door actuators PN 114122012 (Post-Ref. 5 standard) is not 

considered as a terminating action of the repetitive inspections as 

required by this AOT. 

It is anticipated that this AOT being mandatory by EASA new AD with 

supersedure of EASA AD 2006-0112R1 (Ref. 7). 

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4.3 SPARES: 

In case of door actuator replacement, please be advised that actuator PN 

114122011 can be installed in place of actuator PN 114122012 without any conditions or restrictions. 

The current documentation reflects an interchangeability code (ICY) 01 

between PN 114122011 and PN 114122012. The documentation will be revised to 

reflect an ICY 02 between PN 114122011 and PN 114122012. This IPC revision 

is targeted for May 2011 . 

5. FURTHER ACTIONS : 

Airbus recommends A320 Family operators to put on hold the accomplishment of door actuator modification from PN 114122011 to PN 114122012 as per SB 

A320-32-1338 (Ref . 5) and GE AVIATION VSB 200-32-528 (Ref. 6). 

A new Inspection service Bulletin (ISB) applicable to Pre and Post MOD 

38274/SB A320-32-1338 (Ref. 5) actuators will be issued by end of April 2011. This ISB will cover repetitive inspection of Para 4.2.2 and will 

supersede previous ISB A320-32-1309 Rev 02 (Ref. 8). 

6. FURTHER INFORMATION: 

A Flight Operations Telex (FOT) number 999.0008/11 (Ref. 13) has been 

issued to introduce the OEB 209/1 (Ref. 14) for modification of the flight 

crew procedure in case of "L/G GEAR NOT DOWNLOCKED" warning. 

This will introduce a delay of two (2) minutes prior to selecting gravity extension. If the gear extension sequence is interrupted due to a stiff 

door actuator, hydraulic pressure will continue to act to extend the 

actuator during this two minute period . 

7. AOT APPROVAL : 

THE TECHNICAL CONTENT OF THIS AOT HAS BEEN APPROVED UNDER EASA DESIGN 

ORGANIZATION APPROVAL EASA . 21J . 031 . 

8. REPORTING/ACKNOWLEDGEMENT : 

OPERATORS ARE REQUESTED TO ACKNOWLEDGE RECEIPT OF THIS AOT WITHIN 48 

HOURS AFTER RECEIPT TO : 

Mrs. L. BONNET SEEL 

E-mail laetitia.bonnet@airbus. com 

Fax : +33 (0)5 67 19 12 OS 

THIS ACKNOWLEDGMENT CAN BE MADE THROUGH THE AIRBUS FIELD SERVICE OFFICE 

WHERE AVAILABLE. 

QUESTIONS ABOUT THIS AOT AND INSPECTION RESULTS WITH FINDINGS 

ARE TO BE SENT TO AIRBUS CUSTOMER SERVICES ENGINEERING AS SOON AS 

POSSIBLE, AFTER THE AOT APPLICATION, TO THE ATTENTION OF: 

Mr. Jean-Marc Lacanette, SEEL1, 

Phone: +33(0) 5 67 . 19.16. 21 

Fax: +33(0) 5 67.19.12.05 

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E-mail: jean-marc.lacanette@airbus. com 

Best regards. 

A. VIEILLARD 

VICE PRESIDENT A320 FAMILY PROGRAMME 

CUSTOMER SERVICES DIRECTORATE 

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