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CUSTOMER SERVICES DIRECTORATE 2 ROND POINT EMILE DEWOITINE 31700 BLAGNAC FRANCE TELEPHONE + 33 (0)5 61 93 33 33
ALERT OPERATORS TRANSMISSION - AOT AOT ref: A27L014-20 Rev 01 Page 1 of 7 Date: 24-NOV-2020 © AIRBUS S.A.S. 2020. ALL RIGHTS RESERVED. CONFIDENTIAL AND PROPRIETARY DOCUMENT SUBJECT: ATA 27 – THSA lower attachment incorrect installation AIRCRAFT TYPE: A330,A340 OUR REF.: A27L014-20 Rev 01 dated 24-NOV-2020 OUR PREVIOUS REF: A27L014-20 Rev 00 dated 26-MAY-2020 EFFECTIVE DATE: 04-DEC-2020
0. REASON FOR REVISION This AOT was issued in May 2020 (Rev 00) to perform a one-time inspection of the THSA lower attachment part on A/C for which Ref. 2 or Ref. 3 AMM tasks revision of July 2019 (or later) had not been performed. These AMM tasks were revised in July 2019 to allow for the detection of incorrect installation. However, further to operators feedback, they are still unclear and contain a few errors.
Therefore, this AOT is revised (Rev 01) in order to:
-Update the list of affected A/C to include all A330 and all A340-200/-300 except:
oA/C already inspected in accordance with Rev 00 of this AOT which provided correct information to perform the subject inspection, oA/C already inspected by Airbus before Entry Into Service, -Bring the identified errors in Ref. 2 & Ref. 3 AMM tasks to the attention of operators,
- Introduce minor changes to improve clarity, including in Appendixes 1, 2 and 3.
The revised paragraphs are indicated between ***BEG REV*** and ***END REV***.
The modifications are written in blue in Appendixes 1, 2 and 3.
1. AIRCRAFT AFFECTED ***BEG REV*** All A330 aircraft up to MSN 01965 inclusive, except:
MSN 01795, 01813, 01824, 01844, 01861, 01863, 01865, 01874, 01888, 01902, 01907, 01924, 01930, 01934, 01952, 01953, 01956, 01957, 01958, 01959, 01960, 01961, 01962, 01963 and 01964 already inspected by Airbus before Entry Into Service, MSNs which have already been inspected in accordance with Rev 00 of this AOT.
All A340-200/-300 aircraft, except MSNs which have already been inspected in accordance with Rev 00 of this AOT.
***END REV***
2. REFERENCED DOCUMENTATION
2.1 APPENDIX ***BEG REV*** Appendix1-Rev01-Context and photo examples Appendix2-Rev01-Flowchart Appendix3-Rev01-Reporting Sheet ***END REV***
ALERT OPERATORS TRANSMISSION - AOT AOT ref: A27L014-20 Rev 01 Page 2 of 7 Date: 24-NOV-2020 © AIRBUS S.A.S. 2020. ALL RIGHTS RESERVED. CONFIDENTIAL AND PROPRIETARY DOCUMENT
2.2 REFERENCES ***BEG REV*** Ref. 1:
For A330 PRE SB 27-3234: Illustrated Parts Catalog (IPC) 27-44-04-01 /-01B /-01C and for A340 IPC 27-44-04-03:
- Item 310: BOLT, HEXAGON HEAD, CLOSE TOLERANCE - PN NAS1307-3 – QTY 02
- Item 320: WASHER-TAB - PN BSSP108L – QTY 02
- Item 330: PIN – PN FE134-000-45 - QTY 02
- Item 340: WASHER - PN FE134-000-19 - QTY 02 -Item 350: BEARING – PN 11ANZ24 – QTY 02 For A330 POST SB 27-3234 IPC 27-44-04-01D:
- Item 260: BOLT, HEXAGON HEAD, CLOSE TOLERANCE - PN NAS1307-3 – QTY 02
- Item 270: WASHER-TAB - PN BSSP108L – QTY 02
- Item 280: PIN – PN FE134-000-45 - QTY 02
- Item 290: WASHER - PN FE134-000-19 - QTY 02 -Item 300: BEARING – PN 11ANZ24 – QTY 02 NOTE: The item number will be mentioned hereafter in this AOT as follows (item XX / YY) with:
-XX the corresponding item number for A330 PRE SB 27-3234 (IPC 27-44-01 /-01B /-01C) and for A340 IPC 27-44-04-03, -YY the corresponding item number for A330 POST SB 27-3234 (IPC 27-44-04-01D).
Ref. 2: Aircraft Maintenance Manual (AMM) task 27-44-00-210-801-A - Detailed Inspection of Following Items of Trimmable Horizontal Stabilizer (THS) Actuator: Fail Safe Nut, Upper and Lower Attachments (Primary and Seco...
Ref. 3: AMM task 27-44-51-400-801-A (or -C) - Installation of the Trimmable Horizontal Stabilizer Actuator (THSA) Ref. 4: AMM task 55-16-34-200-801-A - Detailed Inspection of Horizontal Stabilizer, Assembly of Trim Actuating Arms, Support Fittings and Upper and Lower Attachment Plates Ref. 5: AMM task 27-44-51-000-801-A ( or -C) - Removal of the Trimmable Horizontal Stabilizer Actuator (THSA) Ref. 6: AMM task 27-44-51-000-804-A - Removal of the Bearing for the Primary Gimbal Joint Ref. 7: AMM task 27-44-51-400-804-A - Installation of the Bearing for the Primary Gimbal Joint NOTE: Unless specifically mentioned, any revision of Airn@v is acceptable for AMM tasks listed in this AOT.
***END REV***
ALERT OPERATORS TRANSMISSION - AOT AOT ref: A27L014-20 Rev 01 Page 3 of 7 Date: 24-NOV-2020 © AIRBUS S.A.S. 2020. ALL RIGHTS RESERVED. CONFIDENTIAL AND PROPRIETARY DOCUMENT
3. REASON
3.1 FACTS ***BEG REV*** Airbus was recently made aware of cases of incorrect installation of Trimmable Horizontal Stabilizer Actuator (THSA) lower attachment parts identified in Ref. 1 IPC chapter:
-Event of cup washer (item 340 / 290) not inserted in pin (item 330 / 280), found in production.
-Event of loose bolt (item 310 / 260) not sufficiently secured by keywasher (item 320 / 270) on a THSA fitted from delivery and found during accomplishment of Ref. 2 scheduled maintenance task (interval 12000FH).
***END REV*** Picture examples of these findings are shown in Appendix 1.
The root cause of this incorrect installation has been attributed to human error in all cases encountered.
***BEG REV*** The instructions for THSA installation have been improved in production. This update has been applied from MSN 01966 and on. Some former aircraft have been inspected before Entry Into Service and are, therefore, excluded from the list of affected A/C (refer to §1 Affected aircraft).
Following the discovery of similar findings occurring on A300-600, a first update to the A330/A340 AMM tasks was made in order to improve clarity on the THSA installation in the July 2019 revision of Airn@v.
After the issuance of Rev 00 of this AOT, errors in Ref. 2 and Ref. 3 AMM tasks were reported as follows:
-Ref 2. Incorrect Figure 27-44-00-991-01000-00-A, -Ref 3. Missing steps for the installation of subject parts on A/C.
Therefore, the accomplishment of Ref. 2 or Ref. 3 AMM task revision of July 2019 (or later) is no longer used to establish the list of affected A/C. Consequently, even A/C for which Ref. 2 or Ref. 3 AMM task revision of July 2019 (or later) have been performed, must be inspected in accordance with this AOT.
Thus, the first step of the flowchart in Appendix 2 has been removed.
The update of the documentation is ongoing (see §5.2 Impacted documentation). Nevertheless, the Rev 01 of this AOT must be privileged during this transition period. Therefore all the affected A/C defined in §1 are required to perform the inspection in accordance with this AOT.
The same lower attachment (parts and assembly) is applicable on both A330 & A340-200/-300 fleet regardless of THSA Part Number. A340-500/-600 fleet is not affected by this AOT due to a different attachment principle.
***END REV***
3.2 CONSEQUENCES ***BEG REV*** The incorrect installation of Ref. 1 parts could lead to bolt (item 310 / 260) separation from the THSA, then followed by the separation of the keywasher (item 320 / 270), the cup washer (item 340 / 290) and ultimately the spherical bearing (item 350 / 300).
***END REV*** NOTE: As per design, the RH bearing moves freely in the THS-actuator arm. The LH bearing is force fitted to the THS-actuator arm. The inspection required in this AOT is valid for both LH and RH sides.
ALERT OPERATORS TRANSMISSION - AOT AOT ref: A27L014-20 Rev 01 Page 4 of 7 Date: 24-NOV-2020 © AIRBUS S.A.S. 2020. ALL RIGHTS RESERVED. CONFIDENTIAL AND PROPRIETARY DOCUMENT This situation is identified as a load sharing condition between the primary and secondary load paths of the THSA.
In case such scenario happens, it would be detected by the Checkable Shear Pin (CSP) implemented by mandatory retrofit on the entire fleet since end of December 2016 as per AD 2014-0219. The CSP detection is announced to the crew by simultaneous ECAM warnings F/CTL PRIM 2 PITCH FAULT and F/CTL PRIM 3 PITCH FAULT.
3.3 AIM The aim of this AOT is to perform a one-time inspection of the THSA lower attachment, ensuring correct installation of Ref. 1 parts and providing corrective actions in case of findings.
4. SHORT TERM ACTION NOTE 1: This AOT is expected to be classified mandatory by an Airworthiness Directive (AD). The accomplishment instructions marked as Required for Compliance (RC) must be done to comply with the AD. “RC” is indicating these paragraphs accordingly.
NOTE 2: The accomplishment instructions of this AOT include procedures given in other documents or in other sections of the AOT. When the words ’refer to’ are used and the operator has a procedure accepted by the local authority he belongs to, the accepted alternative procedure can be used. When the words ’in accordance with’ are used then the given procedure must be followed.
NOTE 3: The access and close-up instructions, not comprising return to service tests, in this AOT do not constitute or affect the technical intent of the AOT. Operators can therefore, as deemed necessary, omit or add access and/or close-up steps to add flexibility to their maintenance operations as long as the technical intent of the AOT is met within the set parameters.
4.1 PLANNING AND MANPOWER
4.1.1 RC - ACCOMPLISHMENT TIMESCALE ***BEG REV*** Aircraft determined affected by §1 of this AOT must be inspected no later than 1000FH from AOT Rev 01 effective date.
***END REV***
4.1.2 MANPOWER ***BEG REV*** The estimated time to perform the THSA inspection on aircraft is 1.30 MH, which is split as follows:
0.50 MH to get access to the THSA area, 0.30 MH to perform Ref. 2 AMM task revision of July 2019 (or later) with use of AOT Appendix 1, 0.50 MH for the close up.
The following additional time is to be considered depending on the findings:
0.50 MH in case of findings during THSA lower attachment parts inspection and necessary replacement/reinstallation of subject parts using Ref. 6 and 7 AMM tasks, 0.20 MH in case of structural inspection required, referring to Ref. 4 AMM task, 24 MH in case of THSA replacement required, referring to Ref. 3 revision of October 2020 (or later) and Ref 5 AMM tasks.
***END REV***
ALERT OPERATORS TRANSMISSION - AOT AOT ref: A27L014-20 Rev 01 Page 5 of 7 Date: 24-NOV-2020 © AIRBUS S.A.S. 2020. ALL RIGHTS RESERVED. CONFIDENTIAL AND PROPRIETARY DOCUMENT
4.2 DESCRIPTION ***BEG REV*** The actions to be performed in the frame of this AOT are described in the flowchart of Appendix 2:
1. Description of the inspection to be performed,
2. Description of the actions in case of findings,
3. Report accomplishment and findings to Airbus.
***END REV***
4.2.1 ACCESS ***BEG REV*** For the inspection, get access to the THSA, refer to ‘’job setup’’ paragraph per Ref. 2 AMM task.
***END REV*** In case of findings, refer to ‘’job setup’’ paragraph per Ref. 3, 4 or 5 AMM task as required.
4.2.2 RC - INSPECTION REQUIREMENTS ***BEG REV*** Verification of the correct installation of both LH and RH sides THSA lower attachment are to be performed by means of a one-time detailed visual inspection on aircraft while referring to the Ref. 2 AMM task revision of July 2019 (or later) and the additional information provided in AOT Appendix 1.
Specific attention must be paid to:
- Pin (item 330 / 280) inserted in one hole of cup washer (item 340 / 290),
- Key of keywasher (item 320 / 270) inserted in the other hole of cup washer,
- Bolt (item 310 / 260) flush with keywasher, itself flush with cup washer and bolt cannot move,
- Both tabs of keywasher folded against 1 or 2 faces of bolt head.
Refer only to AOT Appendix 1 for illustration and not to AMM Figure 27-44-00-991-01000-00-A.
NOTE: The LH and RH bearing assemblies are not identical. The LH assembly has a cotter pin while the RH assembly does not (refer to AMM Figure 27-44-51-991-01100-00-C (SHEET 2/2)).
The parts to be inspected in the frame of this AOT are the same on both sides (the cotter pin is not one of them).
***END REV***
4.2.3 RC - FINDINGS ***BEG REV*** In the event of incorrect installation on one or both sides (correct assembly provided in Appendix 1), the disassembly of the bolt (item 310 / 260), the keywasher (item 320 / 270) and the cup washer (item 340 / 290) on both LH and RH sides will be required for inspection using support of the Ref. 6 AMM task.
These parts will then be reinstalled or replaced depending of their condition using support of the Ref. 7 AMM task.
In any case, the keywasher (item 320 / 270) is considered as a consumable part and will need to be replaced.
NOTE 1: The correct insertion of the pin (item 330 / 280) in one hole of the cup washer will be checked but the pin does not need to be removed.
ALERT OPERATORS TRANSMISSION - AOT AOT ref: A27L014-20 Rev 01 Page 6 of 7 Date: 24-NOV-2020 © AIRBUS S.A.S. 2020. ALL RIGHTS RESERVED. CONFIDENTIAL AND PROPRIETARY DOCUMENT NOTE 2: Ref. 6 and Ref. 7 AMM tasks do not need to be entirely performed as the removal of the bearing (item 350 / 300) is not necessary. They are only mentioned as support for the removal/installation of the bolt (item 310 / 260), the keywasher (item 320 / 270) and the cup washer (item 340 / 290).
NOTE 3: For determining the condition of the removed parts (re-usable or not), industry standard practices or airline policy will be used. In case of doubt, the parts need to be replaced.
***END REV*** Examples of observed incorrect installation are provided in Appendix 1.
***BEG REV*** In case parts are found separated from the THSA:
Inspection referring to the Ref. 4 AMM task will be required and THSA has to be replaced referring to Ref. 3 revision of October 2020 (or later) and Ref. 5 AMM tasks.
***END REV*** In case of findings in the accomplishment of Ref. 4 AMM task, contact Airbus.
4.3 SPARES AND TOOLING ***BEG REV*** For THSA lower attachment spare parts, please refer to Ref.1 IPC chapter for PN and quantities.
Only the bolt (item 310 / 260), the keywasher (item 320 / 270) and the cup washer (item 340 / 290) need to be provisioned.
The bearing (item 350 / 300) and the pin (item 330 / 280) do not need to be provisioned.
No additional specific tooling to the ones called by Ref 2, 3, 4 or 5 AMM tasks are needed.
NOTE: The THS Fixture-Strut Tool PN 98A27407514005 referenced in Ref 6 AMM task is not required as the removal of the bearing is not necessary.
For spare parts order, please contact Collins (FA3T1) at the following address:
GOODRICH ACTUATION SYSTEMS SAS 7-9 AVENUE DE L'EGUILLETTE 95310 SAINT OUEN L'AUMONE FRANCE ***END REV***
5. FURTHER INFORMATION
5.1 FOLLOW-UP PLAN None
ALERT OPERATORS TRANSMISSION - AOT AOT ref: A27L014-20 Rev 01 Page 7 of 7 Date: 24-NOV-2020 © AIRBUS S.A.S. 2020. ALL RIGHTS RESERVED. CONFIDENTIAL AND PROPRIETARY DOCUMENT
5.2 IMPACTED DOCUMENTATION ***BEG REV*** Further to operator feedback following the issuance of the Rev 00 of this AOT, and based on the information provided in Appendix 1, the Ref. 2 & Ref. 3 AMM tasks are subject to a new update for correction and improvement:
- An update to the Figure 27-44-00-991-01000-00-A of Ref. 2 is scheduled for Revision of April 2021.
-The missing steps for the installation of subject parts on A/C in Ref. 3 were added in Revision of October 2020.
***END REV***
6. AOT APPROVAL ***BEG REV*** The technical content of this document is approved by EASA and is expected to be classified mandatory by an AD.
***END REV***
7. REPORTING Questions about this AOT are to be addressed to Airbus Customer Services through TechRequest on Airbus World, selecting Maintenance & Engineering Domain, Engineering Support Section and ATA 27-
40.
As per latest reporting policy (Ref to OIT 999.0018/16), inspection results (with or without findings) are to be addressed to Airbus Customer Services through the generic e-mail address:
inspection.results@airbus.com.
Best Regards, Christian FREMONT
VICE PRESIDENT ENGINEERING SUPPORT
CUSTOMER SERVICES Stéphane GOSSELIN VICE PRESIDENT A330/A340 PROGRAMME
CUSTOMER SERVICES
AOT A27L014-20 Rev 01 - Appendix 1 - Context and photo examples FR88 2312 FR80 1CS SEE 27-41-04 SEE 55-16-07 100 110 120 90 80 70 145 155 165 130 310 140 150 20 360 60 350 330 40 160 50 30 340 320 IPC Figure 27-44-04-03 (for A340) shown as example (Refer to AOT §2.2 according to A/C configuration) Page 1 of 2
AOT A27L014-20 Rev 01 - Appendix 1 - Context and photo examples RH view bolt (item 310 / 260) cup washer (item 340 / 290) LH view 3mm 6L-000-7EV3 LH view LH view Correct Assembly
1. Pin inserted in one hole of cup washer
2. Key of keywasher inserted in the other hole of cup washer
3. Bolt flush with keywasher, itself flush with cup washer and bolt cannot move
4. Both tabs of keywasher folded against 1 or 2 faces of bolt head Incorrect Assembly oin (item 330 / 280) A. Pin not inserted in dedicated hole, preventing flush installation of cup washer keywasher with foldable B. Key and pin inserted in same hole (no picture example) tabs (item 320 / 270) C. Tabs of keywasher insufficiently folded, not preventing bolt head rotation D. Loose or improperly torqued bolt Page 2 of 2