ALERT OPERATORS TRANSMISSION - ALERT OPERATORS TRANSMISSION

AIRBUS CUSTOMER SERVICES

SUBJECT: ATA 25-11-00 SOGERMA PILOT SEAT PN 2510112/2510113-SERIES - UNCOMMANDED 

HORIZONTAL MOVEMENT

OUR REF.: A25W001-12 dated 06-June-2012.

1. AIRCRAFT AFFECTED

All A300-600 / A300-600ST / A310-200 / A310-300 equipped with SOGERMA Powered Captain and 

First Officer Seat PN 2510112/2510113-Series.

2. REFERENCED DOCUMENTATION

2.1 Appendix

Appendix 1 - Flow chart and exploded view.

2.2 References

REF. 1 IPC 25-11-01

REF. 2 AMM 25-11-11 (CAPTAIN SEAT)

REF. 3 AMM 25-11-12 (FIRST OFFICER SEAT)

REF. 4 SOGERMA CMM 25-11-19, Rev 10 dated 15-Mar-2010

REF. 5 SOGERMA CMM 25-11-22, Rev 09 dated 15-Mar-2010

REF. 6 ARTUS CMM 25-13-02 dated Jan-2008

REF. 7 SOGERMA VSB 2510112-25-898 dated 24-Apr-2012

REF. 8 SOGERMA VSB 2510112-25-813 Rev. 03 dated 14-Jan-2010

REF. 9 AIRBUS SB A300-25-6217 dated 31-Aug-2009 for A300-600

REF. 10 AIRBUS SB A300-25-9011 dated 31-Aug-2009 for A300-600ST

REF. 11 AIRBUS SB A310-25-2205 revision 01 dated 19-Nov-2010 for A310

REF. 12 AOT A300-25A6215 Rev. 02 dated 02 MAR 2009

REF. 13 AOT A300-25A9010 Rev. 02 dated 02 MAR 2009

REF. 14 AOT A310-25A2203 Rev. 02 dated 02 MAR 2009

REF. 15 EASA Airworthiness Directive (AD) 2010-0070

REF. 16 FAA Airworthiness Directive (AD) 2011-06-09

3. REASON

3.1 FACTS

An Operator recently reported that, during climb phase of an A310 aircraft, the First 

Officer Seat PN 2510113-55-11 slid back step by step to the end stop position.

Command was transferred to the captain and flight continued uneventful.

After removal of the First Officer seat PN 2510113-55-11, vendor SOGERMA(SOG), it has 

been identified that the reduction gear of the horizontal actuator PN RT19H4FX (vendor 

ARTUS) was damaged.

3.2 BACKGROUND

In 2008, AOTs A300-25A6215 / A300-25A9010 / A310-25A2203 were issued to inform A300-600 / 

A300-600ST / A310 operators of a similar event which occurred on board an A300-600 

aircraft and resulted in SOGERMA First Officer seat PN 2510113-05-14 sliding back by 

itself to the end stop position.

Investigations on the removed reduction gear of the horizontal actuators PN RT19H4FX 

showed that the disc key inside the clutch (reflected in ARTUS CMM 25-13-02 Page 1016 

Figure 2 Item 100 refer to appendix 1) was broken, thus unlocking the seat horizontal 

movement.

Detailed operational check of the seat itself revealed that the actuator operation could 

not be properly stopped by the aft horizontal end stop switch (reflected in SOGERMA CMM 
25-11-19 or CMM 25-11-22 Page 1010-0 Figure 10 Item 480 refer to appendix 1).

At that time, SOGERMA provided VSB 2510112-25-813, covered by Airbus Service Bulletins SB 

A300-25-6217, SB A300-25-9011, SB A310-25-2205 to ensure correct operation of the end 

stop switch avoiding any further damage to the disc key.

This final fix has been rendered mandatory by through EASA AD REF 15 and FAA AD REF 16.

3.3 INVESTIGATION:

Regarding the last event, the investigation on the reduction gear of the horizontal 

actuator PN RT19H4FX removed from First Officer seat PN 2510113-55-11 showed that the 

disc key inside the clutch (reflected in ARTUS CMM 25-13-02 Page 1016 Figure 2 Item 100 

refer to appendix 1) was also broken, thus unlocking the seat horizontal movement.

VSB 2510112-25-813 was previously applied on this removed First Officer Seat.

Detailed operational check of the seat itself revealed that the reduction gear actuator 

operation could not be properly stopped due to following scenario:

- The disc key was broken inside of the clutch, before the VSB 2510112-25-813 embodiment 

addressing the end stop switch issue.

- Further to the disc key breaking-off, a jamming occurred between the gear and the shaft 

of the clutch (reflected in ARTUS CMM 25-13-02 Page 1016 Figure 2 Item 170/60 refer to 

appendix 1), allowing sufficient torque transmission between the gear and the shaft for 

normal pilot seat operation.

- During climb, with the high aircraft incidence generating high longitudinal loads on 

the pilot seat, the jamming between the gear and the shaft was not sufficient to keep the 

First Officer Seat in locked position, leading to a step by step backward movement.

3.4 CONSEQUENCES

The horizontal locking of the Captain/First Officer Seat is no more ensured if jamming 

condition between the gear and the shaft of the actuators PN RT19H4FX

clutch is not sufficient, while high longitudinal loads are applied on the seat.

3.5 AIM

The purpose of this AOT is to request A300-600 / A300-600ST / A310 operators to check the 

horizontal locking function on the Captain and First Officer seats PN 

2510112/2510113-Series, by testing the disc key condition in accordance with the 

instructions of the SOGERMA VSB 2510112-25-898 thus preventing any potential seat 

movement due to a damaged disc key inside of the reduction gear actuator PN

RT19H4FX.

4. SHORT TERM ACTION

4.1 PLANNING AND MANPOWER

4.1.1 ACCOMPLISHMENT TIMESCALE

Accomplishment of SOGERMA VSB 2510112-25-898 has to be performed within the next 6 months 

after the dispatch date of this AOT.

4.1.2 MANPOWER

The estimated time to perform SOGERMA VSB 2510112-25-898 is 0.3 MH per seat.

4.2 DESCRIPTION

4.2.1 ACCESS

N/A

4.2.2 INSPECTION REQUIREMENTS

Inspection of Captain and First Officer Seat PN 2510112/2510113-Series has to be 

performed as per SOGERMA VSB 2510112-25-898 instructions (please refer to Appendix 1. 
Exploded view).

4.2.3 FINDINGS

VSB 2510112-25-898 describes a simple procedure to test the disc key condition, by means 

of a calibrated tensile test sample PN 2510112299-20(Vendor SOGERMA).

The calibrated tensile test sample is screwed between the actuator and the pilot seat 

base that moves horizontally during normal operating conditions.

If the tensile test sample breaks-off, while activating the electrical horizontal control 

switch, the actuator is serviceable.

If the tensile test sample does not break-off, it means that the seat locking function is 

not ensured and it is required, before next flight, to either:

- replace the pilot seat with a serviceable one as per REF 2 and/or REF 3.

- or remove the seat, for replacement of the actuator PN RT19H4FX as per REF 4 and/or 

REF 5.

Note: A sampling has been performed on a representative number of aircraft showing that 

none of the inspected seats required pilot seat or actuator replacement.

4.3 SPARES AND TOOLING

Dedicated information letter will be provided by SOGERMA to support operators in case of 

findings (i.e. tensile test sample does not break-off)

Standard tooling and test kit PN: 25-898-9000 are needed for accomplishment of VSB 

2510112-25-898.

5. FURTHER INFORMATION

5.1 FOLLOW-UP PLAN

An Airworthiness Directive is expected to be issued by EASA, to render mandatory this AOT.

No specific follow-up is foreseen for this AOT, as SOGERMA VSB 2510112-25-898 is a 

one-shot inspection.

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:

Mrs. V. HOLDEN, SEEC

E-mail: valerie.holden@airbus.com

Fax number +33 (0)5 61 93 44 25

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:

Thierry BEUCHARD

Cabin Interior Engineer

Customer Services Engineering - SEEC3

AIRBUS

Phone: +33 (0)5 61 93 86 86

Fax number +33 (0)5 61 93 44 25

E-mail: Thierry.beuchard@airbus.com

Best Regards,
J-L MOUYSSETG. DESESQUELLES

VICE PRESIDENT ENGINEERING SUPPORTHEAD OF A300/A310 FAMILY PROGRAMME SUPPORT

CUSTOMER SERVICESCUSTOMER SERVICES