FROM : AIRBUS CUSTOMER SERVICES

TO : ALL A318/A319/A320/A321 CFMI OPERATORS

ALERT OPERATORS TRANSMISSION ‐ ALERT OPERATORS TRANSMISSION

AIRBUS CUSTOMER SERVICES

SUBJECT: ATA 71 ‐ A318/A319/A320/A321 powered with CFM56‐5A/5B ‐ Failure of aft engine mount

inner retainer bracket

OUR REF.: A71N001‐12 Rev2 dated 27 Feb 2013 OUR PREVIOUS REF.: A71N001‐12 Rev1 dated 09 Aug

2012 OUR PREVIOUS REF.: A71N001‐12 dated 06 Aug 2012.

0. REASON FOR REVISION

Addition of new paragraph for a torque check in case of broken retainer.

Modification of the accomplishment timescale.

No additional inspection is required by this AOT revision for operators who have already

applied A71N001‐12 Rev1 dated 08 Aug 2012 on their A318/A319/A320/A321 fleet.

The revised paragraphs are indicated between **BEG REV** and **END REV**.

1. AIRCRAFT AFFECTED

All A318/A319/A320/A321 powered with CFM56‐5A/5B prior to MSN4942 and on aircraft post MSN 4942

if the aft engine mount has been removed from the aircraft since delivery.

2. REFERENCED DOCUMENTATION

2.1 APPENDIX

Goodrich VSB RA32071‐146 Rev.2

2.2 REFERENCES

A320 AMM 71‐13‐00‐010‐040 Opening of the Fan Cowl Doors

A320 AMM 71‐13‐00‐410‐040 Closing of the Fan Cowl Doors

A320 AMM 78‐30‐00‐481‐041 Make the Thrust Reverser Unserviceable for Maintenance

A320 AMM 78‐30‐00‐081‐041 Make Serviceable the Thrust Reverser after Maintenance

A320 AMM 78‐36‐00‐010‐040 Opening of the Thrust Reverser

A320 AMM 78‐36‐00‐410‐040 Closing of the Thrust Reverser

A320 AMM 71‐22‐11‐000‐042‐A Removal of the Aft Engine Mount without Engine Removal (CFM56‐5A)

A320 AMM 71‐22‐11‐400‐042‐A Installation of the Aft Engine Mount without Engine Removal (CFM56‐

5A)

A320 AMM 71‐22‐11‐000‐043‐A Removal of the Aft Engine Mount without Engine Removal (CFM56‐5B)

A320 AMM 71‐22‐11‐400‐043‐A Installation of the Aft Engine Mount without Engine Removal (CFM56‐

5B) IPC 71‐22‐11‐01(A) Item 100 Inner retainer (3 locations) Goodrich VSB RA32071‐146 Rev.2

3. REASON

3.1 FACTS

During inspections, several operators have found the aft engine mount inner retainer bracket

P/N 238‐0252‐505 broken (IPC 71‐22‐11‐01(A) Item 100 (3 locations)).

For each reported case, the retainer bracket and the outer and inner retainers were still in

place and the pin nut was not loose.
A metallurgical evaluation showed evidence of pitting on the surface of the failed bracket.

This pitting provided stress concentration which enabled crack initiation.

3.2 CONSEQUENCES

The pins which attach the engine link to the aft mount are secured by two nuts; these nuts do

not have a self locking feature, this function being provided by the retainer brackets. In case

of failure of the retainer bracket, the locking feature of the nuts of the inner and outer pins

is lost; as a result these nuts could subsequently become loose.

In case of full loss of the nuts, there is the potential to also lose the pins, in such an

event the aft mount link will no longer be secured to the aft engine mount.

The same locking feature is used for the three link assemblies of the aft mount.

3.3 AIM

There are two types of material finishes possible for the retainers; dull or bright.

The dull finish has the pitted surface and is subject to cracking. The bright finish has a

smooth finish, free of pits.

The purpose of this AOT is to request operators, having aircraft within the affected

population, to inspect the three aft mount retainers and check them for surface finish (dull or

bright), cracks or failure and to replace all non compliant brackets.

4. SHORT TERM ACTION

4.1 PLANNING AND MANPOWER

4.1.1 ACCOMPLISHMENT TIMESCALE

**BEG REV**

Airbus requires that inspection and replacement, as per procedure described in paragraph 4.2,

be carried out as per compliance time specified in EASA PAD 12‐161 and further associated AD

(reference not available at issuance of AOT REV2).

**END REV**

Note that the likelihood of finding is higher on 3766 < MSN < 3818, as these aircraft are

suspected to have been delivered with aft mount retainers having surface pitting.

4.1.2 MANPOWER

1.5 man‐hours estimated per engine for inspection.

1 additional man‐hour estimated per engine if bracket replacement is required.

4.2 DESCRIPTION

4.2.1 ACCESS

Open the fan cowl doors as per AMM Task 71‐13‐00‐010‐040.

Make the thrust reverser unserviceable as per AMM 78‐30‐00‐481‐041.

Open the thrust reverser doors as per AMM Task 78‐36‐00‐010‐040.

Perform the inspection as per paragraph 4.2.2 and replace if necessary as per paragraph 4.2.3.
Close the thrust reverser doors as per AMM task 78‐36‐00‐410‐040.

Make the thrust reverser serviceable as per AMM task 78‐30‐00‐081‐041.

Close the fan cowl doors as per AMM task 71‐13‐00‐410‐040.

4.2.2 INSPECTION REQUIREMENTS

Identify the most accessible surfaces of the inner retainers P/N 238‐0252‐505 (IPC 71‐22‐11‐

01(A) Item 100 (3 locations)) to be inspected and clean these areas before the inspection.

Visually inspect the inner retainers P/N 238‐0252‐505 (IPC 71‐22‐11‐01(A) Item 100 (3

locations)) for surface finish; dull or bright; cracks or failure using 10x magnification,

mirror and light. Refer to Goodrich VSB RA32071‐146 Figure 1 and 2 for examples of non‐

conforming inner retainers P/N 238‐0252‐505 due to surface pitting.

NOTE: The center retainer may be difficult to inspect. In case of doubt, remove the retainer as

per paragraph 4.2.3.1.1 REMOVAL PROCEDURE for inspection.

4.2.3 FINDINGS

For conforming brackets (bright surface finish), no further action is required.

For non‐conforming brackets (dull surface finish) without cracks or not failed, a 50 Flight

Cycle grace period is allowed with an inspection at 25 Flight Cycles. After this period,

replace the bracket as per paragraph 4.2.3.1 REPLACEMENT PROCEDURE and contact Airbus for

reporting purpose.

**BEG REV**

For non‐conforming brackets (dull surface finish) cracked but not failed, replace the bracket

before next flight as per paragraph 4.2.3.1 REPLACEMENT PROCEDURE and contact Airbus for

reporting purpose.

For non‐conforming brackets (dull surface finish) failed, perform the torque check as per

paragraph 4.2.3.0 TORQUE CHECK and then replace the bracket before next flight as per paragraph

4.2.3.1 REPLACEMENT PROCEDURE and contact Airbus for reporting purpose.

4.2.3.0 TORQUE CHECK:

Inspect for a gap between the pin head (AMM item 90) and anti‐rotation bracket (AMM item 100).

Refer to Goodrich VSB RA32071‐146 Figure 1 and 3, AMM task 71‐22‐11‐000‐043 section 4.A.3 for

CFM56‐5B and AMM task 71‐22‐11‐000‐042 section 4.A.3 for CFM56‐5A.

If there is a gap of more than 0.001 inch (0.025mm), the engine weight must be supported by the

engine bootstrap system, install the bootstrap as per paragraph 4.2.3.1.2 BOOTSTRAP

INSTALLATION of this AOT.

Before starting the torque check, apply two lines of ink across nut to bolt.

Check the torque of the 83642‐1420 and the 83642‐918 nuts, by using a torque wrench with an

open‐end type adapter or a torque wrench with a socket. The socket can be no longer than 2.04

inches (51,81mm).

NOTE: The torque value is 80 to 95 lb.ft (108,8 to 128,8 N.m) for the 83642‐1420 nut, and 35 to

42 lb.ft (47,5 to 57 N.m) for the 83642‐918 nut.

Check the existing torque by turning the nut counter‐clockwise slowly in the removal direction

until the point of torque release.
Re‐torque the nut to match the ink lines and read the torque. Verify that the torque values are

met as per NOTE above.

NOTE: Make sure the pin head is aligned with the slot in the retainer prior to re‐torque.

If the nut torque is incorrect contact Airbus for reporting purpose.

Replace the failed retainer as per paragraph 4.2.3.1 REPLACEMENT PROCEDURE **END REV**

4.2.3.1 REPLACEMENT PROCEDURE:

4.2.3.1.1 REMOVAL PROCEDURE:

Without the use of the engine bootstrap system, remove the NAS6303U5 bolts (AMM item 10), the

VN936NP3C washers (AMM item 20), the VN936NP3 washers (AMM item 30), and the NAS1805‐3 nuts

(AMM item 40) that attach the outer retainers to the inner retainers. Retain the hardware for

installation. Refer to Goodrich VSB RA32071‐146 Figure 1, AMM task 71‐22‐11‐000‐043 section

4.A.3 for CFM56‐5B and AMM task 71‐22‐11‐000‐042 section 4.A.3 for CFM56‐5A.

Remove the outer retainers 238‐0253‐509 (AMM item 50) and 238‐0253‐511 (or 238‐0253‐507) (AMM

item 60). Retain the hardware for installation. Refer to Goodrich VSB RA32071‐146 Figure 1, AMM

task 71‐22‐11‐000‐043 section 4.A.3 for CFM56‐5B and AMM task 71‐22‐11‐000‐042 section 4.A.3

for CFM56‐5A.

Inspect for a gap between the pin head (AMM item 90) and anti‐rotation bracket (AMM item 100).

Refer to Goodrich VSB RA32071‐146 Figure 1 and 3, AMM task 71‐22‐11‐000‐043 section 4.A.3 for

CFM56‐5B and AMM task 71‐22‐11‐000‐042 section 4.A.3 for CFM56‐5A.

If there is a gap of more than 0.001 inch (0.025mm), the engine weight must be supported by the

engine bootstrap system, install the bootstrap as per paragraph 4.2.3.1.2 BOOTSTRAP

INSTALLATION of this AOT, then replace the retainer as per paragraph 4.2.3.1.3 RETAINER

REPLACEMENT of this AOT.

If the gap is less than 0.001 inch (0.025mm), replace the retainer as per paragraph 4.2.3.1.3

RETAINER REPLACEMENT of this AOT.

4.2.3.1.2 BOOTSTRAP INSTALLATION:

NOTE: Bootstrap installation is necessary only if a gap is found between the pin head and anti‐

rotation bracket.

Install the Bootstrap system to take the engine weight off of the aft engine mount. Refer to

AMM Task 71‐22‐11‐000‐043, subtask 71‐22‐11‐480‐051 for CFM56‐5B and AMM Task 71‐22‐11‐000‐042,

subtask 71‐22‐11‐480‐050 for CFM56‐5A.

4.2.3.1.3 RETAINER BRACKET REPLACEMENT:

Remove the nuts P/N 83642‐918 (AMM item 130) and P/N 83642‐1420 (AMM item 120). Retain the

hardware for installation. Refer to Goodrich VSB RA32071‐146 Figure 1, AMM task 71‐22‐11‐000‐

043 section 4.A.3 for CFM56‐5B and AMM task 71‐22‐11‐000‐042 section 4.A.3 for CFM56‐5A.

Remove the inner retainer bracket P/N 238‐0252‐505 (AMM item 110) by a conforming one. Refer to

Goodrich VSB RA32071‐146 Figure 1, AMM task 71‐22‐11‐000‐043 section 4.A.3 for CFM56‐5B and AMM

task 71‐22‐11‐000‐042 section 4.A.3 for CFM56‐5A.

Replace the inner retainer bracket P/N 238‐0252‐505 (AMM item 110) by a conforming one. Refer

to Goodrich VSB RA32071‐146 Figure 1, AMM task 71‐22‐11‐400‐043 section 4.G.11 for CFM56‐5B and

AMM task 71‐22‐11‐400‐042 section 4.G.12 for CFM56‐5A.
NOTE: The non‐conforming brackets have to be sent back to Goodrich.

4.2.3.1.4 INSTALLATION PROCEDURE:

Install the 83642‐1420 nut (AMM item 120), 83642‐918 nut (AMM item 130), 238‐0253‐511 (or 238‐

0253‐507) outer retainer (AMM item 60), 238‐0253‐509 outer retainer (AMM item 50), NAS6303U5

bolts (AMM item 10), VN936NP3C washers (AMM item 20), VN936NP3 washers (AMM item 30), and

NAS1805‐3 nuts (AMM item 40). Refer to Goodrich VSB RA32071‐146 Figure 1, AMM task 71‐22‐11‐

400‐043 section 4.G.11 for CFM56‐5B and AMM task 71‐22‐11‐400‐042 section 4.G.12 for CFM56‐5A.

If installed, remove the Bootstrap system. Refer to AMM Task 71‐22‐11‐400‐043, subtask 71‐22‐

11‐080‐050 for CFM56‐5B and AMM Task 71‐22‐11‐400‐042, subtask 71‐22‐11‐080‐051 for CFM56‐5A.

Write in engine log and/or other records that AOT A71N001‐12 dated 27 Jul 2012 and Goodrich VSB

RA32071‐146 have been incorporated.

4.2.3.2 INVENTORY AND SPARES:

Airbus and Goodrich require inspection of all P/N 238‐0252‐505 (IPC 71‐22‐11‐01(A) Item 100) in

inventory and spares. Refer to Goodrich VSB RA32071‐146 Figure 2 for examples of non‐conforming

inner retainers P/N 238‐0252‐505 due to surface pitting.

The non‐conforming brackets have to be sent back to Goodrich for replacement.

4.2.3.3 SHOP (QEC INSTRUCTIONS):

All of the instructions listed in paragraph 4.2.2 and 4.2.3 have to be applied on spare

engines.

4.3 SPARES AND TOOLING

Should you find non‐conforming brackets (dull surface finish), or cracked brackets, refer to

Goodrich VSB RA32071‐146 Material price and availability paragraph for purchase order process.

Refer to A320 AMM tasks listed in referenced documentation for tooling information.

5. FURTHER INFORMATION

5.1 FOLLOW‐UP PLAN

Further actions may be considered based upon results of the ongoing investigations.

5.2 IMPACTED DOCUMENTATION

N/A

6. AOT APPROVAL

The technical content of this document is approved under the authority of DOA nr. EASA.21J.031.

7. REPORTING

Operators are requested to acknowledge receipt of this AOT within 48 hours after receipt to:

Emilie GAILLANOU, SEEE

E‐mail: emilie.gaillanou@airbus.com

Fax number +33 (0)5 61 93 36 14
Questions about this AOT and inspection results, with or without findings, are to be sent to

Airbus Customer Services engineering as soon as possible, after the AOT application, to the

attention of:

Emilien DARTIGEAS

Repair & System Nacelles

Customer Engineering Support ‐ SEEE6

CUSTOMER SERVICES

Phone: +33 (0)5 67 19 09 91

Fax: 33 (0)5 61 93 36 14

Mailto: emilien.dartigeas@airbus.com

Best Regards,

Jean‐Luc MOUYSSET                                                     Frank SCHREIBER

VICE PRESIDENT ENGINEERING SUPPORT         VICE PRESIDENT SA PROGRAMME

CUSTOMER SERVICES                                                     CUSTOMER SERVICES

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