AOT_27A3185_00[1].txt ALL OPERATORS TELEX - ALL OPERATORS TELEX

SUBJECT: ATA 27 – SPOILER SERVO CONTROLS – LOSS OF THE HYDRAULIC LOCKING FUNCTION
OUR REF: AOT A330-27A3185 dated 04 January 2012

1. AIRCRAFT AFFECTED All A330-300 in-service aircraft fitted with MZ-type Spoiler Servo Controls (SSC), Part Number (PN) MZ4339390-12 or PN MZ4306000-12.

2. REFERENCED DOCUMENTATION - Ref.1: Liebherr Component Maintenance Manual (CMM) 27-64-52 Figure 4 Item 210 – Blocking Valve - Ref.2: Liebherr CMM 27-64-52 Figure 4 Item 140 – Maintenance Operator Mechanism - Ref.3: Liebherr CMM 27-64-52 Figure 4 Item 190 – Seal - Ref.4: Airbus Service Bulletin (SB) A330-27-3110 - Flight Controls - Spoiler - Introduce operator mechanism cover - Ref.5: EASA Airworthiness Directive (AD) 2008-0160 – Flight Controls – Spoiler Servo Control Maintenance Cover – Identification / Modification - Ref.6: FAA AD 2009-18-20 - Ref.7: Aircraft Maintenance Manual (AMM) Task 27-64-00-710-802 – Operational Test of the Hydraulic Locking Function on the Spoiler Servo Control - Ref.8: AMM 27-64-52 PB 401 – Servo Control – Spoiler 2,3,4,5,6 – Removal / Installation - Ref.9: AMM 27-64-51 PB 401 – Servo Control – Spoiler 1 – Removal / Installation - Ref.10: Master Minimum Equipment List (MMEL) item 29-09-01 – HYD G(B)(Y) ELEC PUMP FAULT Alert, dated 16 December 2011 - Ref.11: MMEL item 29-20-04 – Yellow Auxiliary Hydraulic power (Electrical Pump), dated 16 December 2011 - Ref.12: Airbus Reporting Sheet RS-SEEL6-2011-686000 - Ref.13: Liebherr-Aerospace Information Notice reference AER/CS/1107-13 - Ref.14: Airbus Technical Follow Up (TFU) 27.64.00.013 – Spoiler SC MZ type – Loss Of Hydraulic Locking Function

3. REASON
3.1. FACTS Two operators have reported several spoilers not remaining in the retracted position after manual depressurization of the corresponding hydraulic circuit during test flights. Subsequent checks on ground confirmed that, for each affected spoiler surface: - The spoiler was fitted with one MZ-type SSC (PN MZ4339390-12 or PN MZ4306000-12) - The maintenance operator mechanism of the SSC was confirmed in the ‘O’ (Operation) position (hydraulic locking function operative). Nevertheless, the spoiler surface could be manually extended.

3.2. SYSTEM DESCRIPTION Page 1AOT_27A3185_00[1].txt Each aircraft is fitted with six pairs of spoilers, identified from position 1 (inboard) to 6 (outboard). Each SSC is controlled by a single flight control computer and supplied by one hydraulic circuit: - Positions 1 (13CS1/13CS2) and 5 (17CS1/17CS2) supplied by Green (G) circuit. - Positions 2 (14CS1/14CS2) and 3 (15CS1/15CS2) supplied by Blue (B) circuit. - Positions 4 (16CS1/16CS2) and 6 (18CS1/18CS2) supplied by Yellow (Y) circuit. SSCs installed in position 1 are not interchangeable with the remaining 2 to 6 SSC positions since the length of the stroke is different. Each SSC is fitted with a blocking valve ref.1, whose purpose is to ensure the hydraulic locking function. This prevents the extension of the spoiler in case of hydraulic depressurization: - If the depressurization occurs when the spoiler is retracted, the SSC remains locked in position. - If the depressurization occurs when the spoiler is extended, the blocking valve allows the retraction under aerodynamic loads. In addition to the blocking valve ref.1, the SSC is fitted with a maintenance operator mechanism ref.2, which allows the de-activation of the locking function for maintenance purposes. During normal operation, the maintenance operator mechanism is set to the ‘O’ (Operation) position, and the hydraulic locking function is operative. When the maintenance operator mechanism is set to the ‘M’ (Maintenance) position, the hydraulic locking function is de-activated, and the spoiler can be manually extended for maintenance purposes.

3.3. INVESTIGATIONS
3.3.1 SHOP FINDINGS The investigation of the affected SSCs at Liebherr revealed that the loss of the hydraulic locking function was due to an internal leakage caused by a sheared seal ref.3. This seal is installed at the left end of the blocking valve ref.1.

3.3.2 PREVIOUS MODIFICATION From 2008 to 2010, all MZ-type SSCs were modified to the current PN MZ4339390-12 (position 1) and PN MZ4306000-12 (position 2 to 6) as per ref.4 Airbus SB. This modification was mandated by ref.5 and ref.6 ADs.

3.3.3 SUSPECTED ROOT CAUSE Most MZ-type SSCs were modified on-wing. During this on-wing modification, the ref.2 maintenance operator mechanism was removed, allowing a possible untimely migration of the ref.1 blocking valve out of its groove. It is suspected that this untimely migration is the root cause for the sheared ref.3 seal events.

3.4. CONSEQUENCES Page 2AOT_27A3185_00[1].txt As long as the corresponding hydraulic circuit is pressurized, this failure has no impact on the operation of the spoilers. Nevertheless, in case of loss of the hydraulic locking function, the SSC is no longer able to remain in the retracted position in the event of a depressurization of the related hydraulic circuit. Therefore, the spoiler surface would extend up to the zero-hinge moment position, which mainly depends on the aircraft speed and on the Flap/Slat configuration. This failure mode (internal leakage) cannot be detected by the flight control computers monitoring, and will remain as hidden until the associated hydraulic system is depressurized in flight. Should an untimely deflection in flight occur, this is announced to the crew via the ECAM warning F/CTL SPLR FAULT and the F/CTL Page on the System Display. On ground, only the application of the test of the hydraulic locking function as per AMM ref.7 ensures the identification of faulty SSCs.

3.5. AIM The aim of this AOT is to confirm the reliable functioning of the MZ-type SSCs currently installed on aircraft by means of a one-time test as per the new ref.7 AMM task. It is anticipated that this AOT will be rendered mandatory by an EASA AD.

4. REQUIRED ACTION
4.1. PLANNING AND MANPOWER The following corrective plan needs to be performed, as per paragraph 4.2, on all in-service affected aircraft: - Within 90 days from receipt of this AOT: * Identification of the concerned aircraft * Test of the MZ-type SSC(s) - In case of findings: * Corrective actions to be accomplished before further flight on the SSCs related to the Blue hydraulic circuit * Corrective actions to be accomplished within 24 months on the SSCs related to the Yellow and Green hydraulic systems - Reporting within 30 days after accomplishment of the corrective actions Spare units are not affected by the requirements of this AOT, because the hydraulic locking function is tested after any shop repair prior to EASA Form 1 issuance. Consequently: - This AOT is only applicable to MZ-type SSC(s) already installed on in-service aircraft at the time of issuance of this AOT - Aircraft which are not fitted with any MZ-type SSC are not affected by this AOT

The application of this AOT requires: - Five man-hours and one hour elapsed time for the application of the ref.7 AMM task Page 3AOT_27A3185_00[1].txt - Additional three man-hours per SSC replacement.

4.2. DESCRIPTION 4.2.1. IDENTIFICATION/TEST OF AFFECTED AIRCRAFT Within 90 days from receipt of this AOT: 1.Identify all aircraft fitted with at least one MZ-type SSC. Note that: - PN MZ 4339390-12 is installed in positions 1 only. - PN MZ 4306000-12 is installed in positions 2 to 6. The two following procedures are approved for the identification: - Use the data from operator approved records. - Read the data by visual inspection on aircraft. On aircraft which are not fitted with any MZ-type SSC, no further action is required by this AOT. 2.At each position fitted with a MZ-type SSC, perform the test of the hydraulic locking function as per ref.7 AMM.

4.2.2 CORRECTIVE ACTIONS 1.On Blue hydraulic circuit, for MZ-type SSC in position 2 and 3 (14CS1, 14CS2, 15CS1, 15CS2): - If the test is successful: No further action is required - If the test fails: BEFORE FURTHER FLIGHT, interchange with a successfully tested unit from another circuit or replace with a spare part the faulty SSC(s), as per ref.8 AMM. 2.On Green hydraulic circuit, for MZ-type SSC in position 1 and 5 (13CS1, 13CS2, 17CS1, 17CS2): - If the test is successful: No further action is required - If the test fails, or if an unsuccessfully tested SSC is installed in position 5 after interchange with Blue circuit: Within 24 months from AOT receipt, replace the faulty SSC(s) with a spare part as per ref.8 or ref.9 AMM. 3.On Yellow hydraulic circuit, for MZ-type SSC in position 4 and 6 (16CS1, 16CS2, 18CS1, 18CS2): - If the test is successful: No further action is required - If the test fails, or if an unsuccessfully tested SSC is installed after interchange with Blue circuit: * Within 24 months from AOT receipt, replace the faulty SSC(s) with a spare part as per ref.8 AMM provided that, before replacement of the faulty SSC(s), the affected aircraft is not dispatched with the Yellow Electric Motor Pump (Y EMP) inoperative as per ref.10 and ref.11 MMEL. * Once all the faulty MZ-type SSC(s) are removed from the Yellow hydraulic circuit: - Dispatch capability with the Y EMP inoperative is restored as per ref.10 and ref.11 MMEL. Page 4AOT_27A3185_00[1].txt - Report the retrofit completion as per paragraph 4.2.3.CAUTION: In order to prevent the installation of faulty units on nonaffected aircraft, only the interchange between positions of the same aircraft is acceptable. ADVICE: Due to spare restriction (refer to 4.3): - It is acceptable to interchange with a unit successfully tested from another circuit of the same airplane, or to replace with a spare part, the faulty SSC(s) identified in positions 2 and 3 (14CS1, 14CS2, 15CS1, 15CS2). - It is acceptable to install or to keep installed unsuccessfully tested SSC(s) in positions 1, 4, 5, and 6. This approach allows: * Up to two SSCs PN MZ4339390-12 without hydraulic locking capability per aircraft. * Up to six SSCs PN MZ4306000-12 without hydraulic locking capability per aircraft.

4.2.3 DATA REPORTING Step 1 For all aircraft fitted with at least one MZ-type SSC, within 30 days after accomplishment of the test as per paragraph 4.2.1, report the test results to the Airbus contact given in paragraph 7 by means of the Reporting Sheet ref.12. Step 2 For all aircraft fitted with at least one unsuccessfully tested SSC on the Yellow hydraulic circuit, within 30 days after replacement of the faulty SSC(s) of the Yellow circuit as per paragraph 4.2.2, report the retrofit completion to the Airbus contact given in paragraph 7 by means of Reporting Sheet ref.12.

4.3. MATERIAL - TOOLING No specific tooling is required for the inspection. Concerning spares, Liebherr-Aerospace is currently facing a difficult supply chain situation on SSC PN 1386x and 1387x –current production standard– due to the fire damage suffered by Liebherr-Aerospace manufacturing plant in Brazil (ref.13). Airbus and Liebherr-Aerospace will increase the spares stock, planned to reach 60 units by June 2012. Nevertheless, the current number of available spares remains insufficient to provide advanced spare parts to all operators prior to application of this AOT. Consequently, spare units will be supplied on AOG basis to operators if and only if more than six SSCs PN MZ4306000-12 are found faulty on the same aircraft and no spares are available at the operator’s warehouse. Spare units have been positioned in Singapore, Europe and the USA in order to reduce the delivery lead-time. AOG orders should be addressed to: Region: Europe, Africa, Middle East Liebherr-Aerospace Lindenberg GmbH (LLI) Phone: +49 8381 46 4868 e-mail: spares.lli@liebherr.com 24 Hrs/7 Days Spares AOG Hotline: +49 171 852 7304 Page 5AOT_27A3185_00[1].txt Region: Americas Liebherr-Aerospace Saline, Inc (LSL) Phone: +1 734 944 6378 e-mail: keith.turczyn@liebherr.com 24 Hrs/7 Days Spares AOG Hotline: +1 313 580 7262 Region: Asia-Pacific Liebherr-Aerospace Singapore Pte. Ltd. (LSI) Phone: +65 6265 2305 e-mail: charles.loke@liebherr.com 24 Hrs/7 Days Spares AOG Hotline: +65 9625 1607According to the feedback as per paragraph 4.2.3, Airbus and LiebherrAerospace will establish a replacement plan of the faulty SSCs fitted on Green and Yellow hydraulic circuits. Throughout this AOT campaign, loan units will be used to cover the spare needs during the turnaround time of the faulty SSC(s) in-shop repair. Process will be monitored by Airbus and planned in accordance with operators’ situation and availability.

5. FURTHER ACTION Follow-up of this AOT will be ensured by means of ref.14 TFU that will be issued by the end of January, 2012.

6. AOT APPROVAL The technical content of this AOT has been approved under EASA Design Organization Approval EASA.21J.031. The content of this AOT is expected to be rendered mandatory by the Airworthiness Authorities.

7. REPORTING / ACKNOWLEDGEMENT Operators are requested to acknowledge receipt of this AOT within 48 hours after receipt to: Mlle Laetitia BONNET, SEEL Phone number: +33 (0)5 67 19 24 40 Fax number: +33 (0)5 61 93 32 73 E-mail: laetitia.bonnet@airbus.com This acknowledgement can be made through the Airbus RCSR office when available. Questions about the technical content of this AOT, and inspection results, with or without findings, are to be sent to Airbus Customer Services, Engineering and Technical Support, attention of: Mr. Daniel LOPEZ FERNANDEZ, SEEL6 Phone number: +33 (0)5 61 93 04 52 Fax number: +33 (0)5 61 93 32 73 E-mail: daniel.lopez-fernandez@airbus.com
Best Regards, Page 6AOT_27A3185_00[1].txt
P.GOURDON VICE PRESIDENT A330/A340 PROGRAMME CUSTOMER SERVICES DIRECTORATE

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