ALERT OPERATORS TRANSMISSION - ALERT OPERATORS TRANSMISSION

AIRBUS CUSTOMER SERVICES

SUBJECT: ATA 29 - CHECK VALVE CAR401 - REPETITIVE INSPECTION POST MOD 201384 OR SB 

A330-29-3119 R02 / A340-29-4091 R02 (400 N.m TORQUE APPLICATION)

OUR REF.: A29L001-12 dated 11 OCT 2012

1. AIRCRAFT AFFECTED

All A330 aircraft that have embodied modification 201384 and SB A330-29-3119 at any 

revision issue

All A340-200/300 aircraft that have embodied SB A340-29-4091 at any revision issue.

2. REFERENCED DOCUMENTATION

2.1 APPENDIX

Reporting sheet.

2.2 REFERENCES

Ref.1: OIT 999.0073/12 dated 21 September 2012

Ref.2: AIRBUS modification 201384: Hydraulic power. Main hydraulic power tighten plug of 

check valve CAR401 with increased torque value

Ref.3: Service Bulletin A330-29-3119 / A340-29-4091 Hydraulic power. Main hydraulic power 

tighten plug of check valve CAR401 with increased torque value

Ref.4: EASA AD NÂ° 2012-0070 dated 25 April 2012

Ref.5: AMM 29-11-53 PB401 Manifold Green Hydraulic System, AMM 29-12-53 PB 401 Manifold 

Blue Hydraulic System, AMM 29-13-53 PB401 Manifold Yellow Hydraulic System

Ref.6: TFU 29.10.00.034 Check valve PN CAR401: hydraulic leakage due to loosening.

3. REASON

Recent reports received by AIRBUS regarding the in-service behaviour of the post Ref.2 or 

Ref.3 check valves, have led to the decision to recommend a repetitive inspection of the 

check valve fitted with an increased torque.

For more background, please refer to Ref.1 and Ref.6.

3.1 FACTS

In the recent months, AIRBUS has received several reports of post Ref.2 or Ref.3 check 

valves exhibiting signs of rotation (red marking not aligned) with the lockwire reported 

broken in some instances.

In one particular case, on an A330 post mod Ref.2 aircraft having accumulated 900 FC/ 

5500 FH the loosening resulted in the loss of the Yellow system and an In Flight Turn 

Back.

On another case, an A330 post mod Ref.2 aircraft having accumulated 800 FC/ 5000 FH, 

signs of loosening (red marking not aligned) were observed on the check valves of the 3 

systems with lockwire broken on the Green system.

3.2 CONSEQUENCES

The loosening of the check valves P/N CAR401 may result in a hydraulic leak and 

ultimately in the loss of the associated hydraulic system.

3.3 AIM

The aim of this AOT is:
- to recommend to perform a repetitive inspection of the check valves PN CAR401 on post 

Ref. 2 and Ref.3 aircraft, to detect any signs of loosening and assess the efficiency of 

the torque increase modification.

- to advise the A330 and A340-200/300 operators to put on hold the application of the 

Ref.3 service bulletins on in-service aircraft mandated by Ref.4 AD until further notice. 

At this stage, the modification Ref.2 remains incorporated on production aircraft until 

definition of the solution to this issue.

4. SHORT TERM ACTION

For all A330 aircraft post mod Ref.2 and all A330 and A340-200/300 post service bulletin 

Ref.3, perform a repetitive visual inspection of the CAR401 check valves on the 3 

hydraulic systems.

4.1 PLANNING AND MANPOWER

4.1.1 ACCOMPLISHMENT TIMESCALE

Within 1000 FH after the issuance date of this AOT, perform the inspection actions 

defined in para 4.2.

Then, repeat the inspection actions defined in para 4.2 every 900 FH.

4.1.2 MANPOWER

It is estimated that a total of 2 manhours will be necessary to get access to the 

inspection area, perform the visual inspection of the check valves and do the close-up. 

In case of findings (sign of rotation or broken lockwire), 1 additional hour might be 

necessary.

4.2 DESCRIPTION

The visual inspection of the Green, Blue and Yellow High Pressure manifolds and check 

valves P/N CAR401 assembly consists of checking any sign of rotation of the check valve 

head. In case of finding corrective action must be applied.

4.2.1 ACCESS

Gain access to the Main Landing Gear Bay area and apply the safety precautions as 

described in the AMM REF 5:

- Put WARNING NOTICE(S) in position to tell people not to pressurize the Green, Blue 

and/or Yellow hydraulic system:

- In the cockpit, on the panel 245VU,

- On the ground service panel of the Green, Blue and/or Yellow hydraulic system, access 

door 197BB, 195BB or 196BB as applicable.

- If needed, in case of finding, put a CONTAINER 5 L (1.32 USGAL) below the check valves 

to collect the hydraulic fluid leakage.

4.2.2 INSPECTION REQUIREMENTS

Visually inspect the Green, Blue and Yellow HP manifold and check valves P/N CAR401 (FIN 

5316JM101, 5316JM102, 5316JM201, 5316JM301) and check their red paint marking for any 

signs of rotation. Check also for any signs of hydraulic fluid leakage or seepage.

In case of finding, before next flight, perform the instructions in para 4.2.3. Fill in 

the reporting sheet attached in appendix and send it to Airbus. Then repeat inspection 

actions defined in para 4.2 every 900FH.

In case of no finding (no sign of rotation, no sign of hydraulic seepage), perform the 

close-up procedure of the AMM Ref. 5. Fill in the reporting sheet attached in appendix 

and send it to Airbus. Then repeat inspection actions defined in para 4.2 every 900FH.

The inspection results will be used by Airbus in order to define the next course of 

action regarding CAR401 check valve loosening.

4.2.3 FINDINGS
(a) If signs of rotation have been observed (red marking not aligned and/or lockwire 

broken), but if no seal distress or black deposit / hydraulic fluid seepage has been 

observed,

- Record the distance between the original paint markings and take a photo if possible

- Cut and discard the lockwire

- Using a calibrated dynamometric wrench, apply a torque of 141 to 143 N.m (103.98 to 

105.45 lbf.ft) to the applicable CAR401 check valve.

- Record the distance between the original markings (and take a photo if possible).

- Remove the original paint marking and apply a new thin paint line on the check valve 

and manifold as per AMM task 20-23-22.

- Install a new lockwire (material NÂ°19-010) as per AMM 20-11-11.

- Remove the placard PN F8537020725000 (CAR401 400 N.M OFF A/C) .

- Perform the test and close-up procedures as per AMM Ref.5.

- Fill in the reporting sheet and send it to AIRBUS at the earliest opportunity.

(b) If seal distress or black deposit /hydraulic seepage has been observed.

- Cut and discard the lockwire.

- Remove the applicable check valve following AMM Ref.5.

NOTE 1: It is highly probable that the initial torque has been lost and it is advised to 

apply no more than 143 N.m torque to loosen the check valve on aircraft.

NOTE 2: In case a higher torque value is required to remove the check valve, it is 

necessary to remove the manifold from the aircraft as per AMM Ref.5.

- Replace the seals as per AMM Ref.5.

- Install the removed check valve as per AMM Ref.5.

- Using a calibrated dynamometric wrench, apply a torque of 141 to 143 N.m (103.98 to 

105.45 lbf.ft) to the applicable CAR401 check valve.

- Record the distance between the markings (and take a photo if possible).

- Remove the original paint marking and apply a new thin paint line on the check valve 

and manifold as per AMM task 20-23-22.

- Install a new lockwire (material NÂ°19-010) as per AMM 20-11-11.

- Remove the placard PN F8537020725000 (CAR401 400 N.M OFF A/C).

- Perform the test and close-up procedures as per AMM Ref. 5.

- Fill in the reporting sheet and send it to AIRBUS at the earliest opportunity.

NOTE 3: even in case of finding on only one check valve from the Green manifold on which 

2 valves are installed, the placard (CAR401 400 N.M OFF A/C) must be removed.

4.3 SPARES AND TOOLING

Refer to AMM Ref. 5

NOTE 4: at each replacement of a check valve P/N CAR401, a torque of 141 to 143 N.m 

(103.98 to 105.45 lbf.ft) must be applied to the replacement check valve P/N CAR401 

during installation.

5. FURTHER INFORMATION

5.1 FOLLOW-UP PLAN

It is anticipated that the content of this AOT will be rendered mandatory by the EASA. It 

is expected that a new AD superseding REF 4 will be issued shortly.

Airbus has launched further engineering activities aiming to define a solution that will 

be the terminating action to the repetitive inspection introduced by this AOT.

Further follow-up will be ensured through TFU Ref.6.

5.2 IMPACTED DOCUMENTATION

Airbus has launched a review of the AMM tasks Ref. 5 to make them aligned with the 

content of this AOT. It is expected that a Temporary Revision will be issued early 

November 2012.

6. AOT APPROVAL

The technical content of this AOT 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:

Laetitia BONNET, SEEL

E-mail: laetitia.bonnet@airbus.com

Fax number +33 (0)5 67 19 12 05

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:

AndrÃ© DONNADIEU

Engineer

Hydraulic Systems - SEEL4

Customer Services

Phone 33 5 61 18 23 21

Fax 33 5 67 19 12 05

Mail to: andre.donnadieu@airbus.com

And

Stephane ACOSTA

Engineer

Hydraulic Systems - SEEL4

Customer Services

Phone 33 5 61 93 04 11

Fax 33 5 67 19 12 05

Mail to: stephane.acosta@airbus.com

Best regards.

Jean-luc MOUYSSETPhilippe GOURDON

VICE PRESIDENT ENGINEERING SUPPORT VICE PRESIDENT 

A330/A340 PROGRAMME

CUSTOMER SERVICES 

CUSTOMER SERVICES