### Sub,iectATA27~ELEVATORMECHANICAL CONTROLLINKAGE

## #CHECKFORCORRECTIN :UNCOUPLINGUNIT De AOT-Dispatch, AIRBUS [mailto:Airbus ..AOT-Dispatch@airbus.com] Envoye jeudi 18novembre 2010 10:01 Objet :ATA 27 -ELEVATOR MECHANICAL CONTROL LINKAGE #CHECK FOR CORRECT INSTALLATION OF THE PITCH UNCOUPLING UNIT FROM AIRBUS CUSTOMER SERVICES TOULOUSE ALL OPERATORS TELEX -ALL OPERATORS TELEX SUBJECT; ATA27
-ELEVATOR MECHANICAL CONTROL LINKAGE -CHECK FOR CORRECT INSTALLATION OF THE PITCH UNCOUPLING UNIT OUR REF: AOT 27A6068 

### rev 01dated 18November 2010 OUR PREVIOUS REF: AOT 27A6068 dated 18November 2010 O.REASON FORREVISION The attached file was not the good version.
I.AIRCRAFT AFFECTED All A300-600 in-service aircraft.

Elevator Control Elevator Control Linkage Unit Linkage 2.REFERENCED DOCUMENTATION

-Ref.l: IPC 27-31-07 Figure 16 Item 100: Mechanism Assy, Locking, pitch uncoupling

-Ref.2: IPC 27-31-07 Figure 16 Item 110: Rod Assy, Control

-Ref.3: Aircraft Maintenance Manual (A~M) 27-30-00 Figure 001: General Description

-Ref.4: Illustrated parts Catalog (IPC) ~7-31-01 Figure 02 Item 190: Control Install pitch Captain
-Bellcrank Assy, Pitch control

-Ref.5: IPC 27-31-07 Figure 04 Item 60: Detent Bellcrank and Lever - Bellcrank Assy, Override Unit

-Ref.6: AMM 27-31-00 Page Block 501 section 2.(1) Operational test, To check correct operation ofpitch uncoupling solenoid

-Ref.7: Maintenance Planning Document (MPD) task number 273100-01-1· Operational Check Of Pitch Control Uncoupiing Using "TEST-OK" Facility On Lateral Panel

-Ref.8: AMM 27-31-00 Page Block 501 section 3.(2): Functional test of pitch control uncoupling and coupling

-Ref.9: MPD task number 273100-02-1: Functional Check Of Pitch Control Uncoupling And Coupling

-Ref.IO: AMM 27-31-33 Page Block 401: Pitch Uncoupling Unit-Removal !Installation
3.REASON 

### 13.1 FACTS

During routine maintenance check on anA300-600, one operator found the pitch uncoupling unit Ref.l installed at an incorrect location, i.e. inverted with the rod assembly Ref.2. After complete inspection of its fleet, the operator identified the same incorrect installation on another aircraft. 3.2 SYSTEM DESCRIPTION The inputs from the control columns are transmitted to the elevators by dual control channels, each channel routed along one side of the fuselage. Refer toRef.3. The left and right control channels are interconnected at two points by two detent bellcranks, one forward bellcrank Ref.4 beneath the flight compartment floor, the other rear bellcrank Ref.5 between the two elevators. The two elevator control channels can be uncoupled during the takeoff and landing phases in the event of jamming of one control channel, bymeans of the two detent bellcranks Ref.4 and Ref.5. Apitch uncoupling unit Ref.l prevents any inadvertent uncoupling of the two elevator control channels after the take-off, inorder toprevent asymmetrical loads being applied to the structural attachments of the trimmable horizontal stabilizer. The pitch uncoupling unit solenoid (4CF) is energized if airspeed is higher than 30 kts and lower than 195 kts. The two elevator control channels can then be uncoupled in the event of jamming. 3.3 INVESTIGATIONS The incorrect installation will not bedetected during the accomplishment of thepitch uncoupling Operational test AMM Ref.6, required every 2000 Flight Hours (FH) or 36 months (MO) as per MPD Ref.7. This test only validates the condition of thepitch uncoupling solenoid. The incorrect installation can only be detected during the accomplishment of the pitch uncoupling Functional test as per AMM Ref.B, required every 18000 FHor 120 MO asper MPD Ref.9. Both aircraft identified with the incorrect installation had never passed the Functional test since their entry into service.


### 23.4 CONSEQUENCES

Would thepitch uncoupling unit Ref,l be inverted with the rod assembly Ref.2, the pitch uncoupling duririgthe takeoff and landing phases in the event of jamming isnomore possible. 3.5AIM Airbus recommends toperform the actions defined in this AOT to ensure a reliable function of the elevator control columns bymeans of aone time visual inspection, to check the correct installation of the pitch uncoupling unit Ref.l and to restore the system if needed. It is anticipated that this AOT will be rendered mandatory by anEASA Airworthiness Directive.
4.SHORT TERM ACTION 4.1 PLANNING AND MANPOWER Airbus requires that, onA300-600 andA300-600ST, the correct pitch uncoupling installation isvisually checked on aircraft onwhich the pitch uncoupling Functional test Ref.S has never been performed since original aircraft delivery. This functional test is required every IS000FH or 120MO asper MPD Ref.9. This AOT isapplicable only to aircraft wnich have not accomplished this MPD Ref.9yet. On applicable aircraft, thevisual inspection must be accomplished within 30 days from theAOT issuance date. The visual inspection represents 2.00 man-hours, with anaddition of 4.00 man-hours in case of necessary corrective actions.
4.2 INSPECTION /CORRECTIVE ACTIONS On applicable aircraft, the following procedure shall be applied:

-Visually check that the pitch uncoupling unit Ref.l is installed at the right location asper AMM Ref.IO.

- If the installation is correct:

aNo further action is required.


### 3- If the installation isnot correct: oRemove and re-install at the correct location the pitch uncoupling unit and the rod assembly, asper AMM Ref.10. Perform the necessary adjustments so that riggings are correct.
a Perform the Functional test of the pitch uncoupling unit as per AMM Ref.8. 4.3 DATA REPORTING Report the inspections findings to theAitbus contact point given in paragraph 7. 4.4 MATERIAL AND TOOLING Neither specific material nor tooling is required for these actions.
S.FURTHER ACTION Arevision of thepitch uncoupling replacement task AMM Ref.lO has been launched byAirbus inorder to clarify which test isrequired after replacement.
6.AOT APPROVAL The technical content of this AOT has bee~ approved under EASA Design Organization Approval EASA.21J.031.
7.REPORTING /ACKNOWLEDGEMENT Operators are requested to acknowledge receipt of this AOT within 48 hours after receipt to: MIle Laetitia BONNET, SEEL Phone number: +33 (O}S 67 19 24 40 Faxnumber: +33 (OJ 5 61 93 32 73 E-mail· Laetitia.bonnet@airbus.com This acknowledgement canbe made through the Airbus RCSR office when available. Questions about the technical content of this AOT, and inspection results, with orwithout findings, are tobe sent toAirbus Customer Services, Engineering and Technical Support, attention of: Mr. Stephane ROBINAUD, SEEL6 Phone number: +33 (0)5 67 19 08 81 Faxnumber: +33 (0)5 61 93 32 73 E-mail: stephane.robinaud@airbus.com Best regards, 

### 4E. VAN AELST

VICE PRESIDENT A300 PROGRAMME CUSTOMER SERVICES DIRECTORATE



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