Messier-Dowty SA SPECIAL INSPECTION

BP 10 - 78142 Vélizy Cedex - France 

Tél: +33 (1) 46 29 18 00 - Fax: +33 (1) 46 29 87 70 

Télex: 634156F - Sita: QBHMDCR 

SERVICE BULLETIN 

A300B4, A300-600, A300-600ST

LANDING GEAR MLG ACTUATING CYLINDER 

NDT INSPECTION OF THREAD OF THE ROD

1. PLANNING INFORMATION

A. Effectivity 

Units affected 

 A300B4 

Actuating cylinder assy 

C23129 and derived parts 

Stripped actuating cylinder 

C23130 and derived parts 

 A300-600, A300-600ST 

Actuating cylinder assy 

C23129004 and derived parts 

Stripped actuating cylinder 

C23130004 and derived parts 

B. Concurrent Requirements 

None 

C. Reason 

To check that the thread of the rod is free from crack. 

D. Description (see figures 1 to 3)

(1) The accomplishment of this Special Inspection Service Bulletin consists in carrying out in 

the workshop an Eddy current inspection of the rod to detect any possible presence of 

material defect. 

October 27, 2005 Service Bulletin N° 470-32-806

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SERVICE BULLETIN 

(2) Flowchart inspection 

No defect 

Replace the rod before the 

next flight 

Return in service

Defect found 

NDT inspection of the MLG Actuating cylinder rod 

E. Compliance 

(1) This Service Bulletin is recommended at the first opportunity. 

(2) Refer to AIRBUS Service Bulletin N° A300-32-0450, A300-32-6097, A300-32-9013.

F. Approval 

The technical content of this Vendor Service Bulletin has been approved under the authority of 

EASA Design Organisation Approval No. EASA.21J.031. 

G. Manpower 

1 NDT specialist (minimum qualification equivalent to level 2 of COSAC/COFREND) 

Estimated time for the Eddy current inspection: 1 hour for each leg 

Estimated time required for accomplishment of this Service Bulletin :Man-hour: 2.50 hours for 

each leg 

NOTE : It is assumed that the equipment has been placed in a maintenance status. The manhour estimates do not include time to prepare or administrative functions. 

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H. Weight and Balance 

None 

I. Electrical Load Data 

None 

J. References 

- Components Maintenance Manuals : 

- Actuating cylinder 

A300B4 32-34-46, 32-34-47 

A300-600, A300-600ST 32-34-48 

- AIRBUS Service Bulletin N° A300-32-0450, A300-32-6097, A300-32-9013. 

K. Other publications affected 

None 

L. Interchangeability or Intermixability of Parts

None 

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2. MATERIAL INFORMATION

A. Material - Price and availability 

(1) Necessary parts : 

Washer C69066 : Qty per actuating cylinder : 1 

Cotter pin MS24665-283 : Qty per actuating cylinder : 1 

Cotter pin MS24665-287 : Qty per actuating cylinder : 1 

(2) The parts that are necessary to perform this Service Bulletin are available to operators on 

request from the regional Messier Dowty Customer Support Centre. 

(3) The parts, are provided at no charge to the operators. 

B. Material Necessary for each Unit. 

None 

C. Tooling – Price and availability. 

Complete tool box KT 69029/-1-2 including 

- 1 specific probes A4A02SB806, frequency 0,5 MHz (see figure 2) 

- 1 calibration block used for defect evaluation. 

- Calibration block CF04C10 contains an artificial defect located on the thread to be checked. 

Eddy Current equipment: Elotest B1 manufacturer: Rohmann or equivalent 

connection: B1-NOB 8H – Rohmann (depend of equipment) 

NOTE: For Nortec equipment, (19E, etc...) no adaptator needed. For others devices an 

adaptator is mandatory. 

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SERVICE BULLETIN 

3. Accomplishment instructions

A. General 

The rod is to be inspected in the workshop, the actuating cylinder having been removed from the 

aircraft, Refer to airbus Service Bulletin A300-32-0450 or A300-32-6097 or A300-32-9013. 

B. Procedure (see figures 1 to 3) 

Inspection of actuating cylinder in the workshop. 

(1) Determination of the position of the end fitting on the rod (see figure 3). 

- Record dimensions L 2 before removing the end fitting refer to CMM relevant to each 

actuating cylinder (see paragraph 1.J). 

(2) Partially disassemble the actuating cylinder, refer to CMM relevant to each actuating 

cylinder (see paragraph 1.J) so that the thread of the rod can be inspected (see figure 1). 

(3) Eddy current inspection NDT inspection 

Calibration of the test equipment 

The set up here after is given for example using a Rohmann machine. 

- Switch on B1, and check battery level. 

- Connect the probe. 

- Check that alarm and gates are off 

- Select frequency to 0,5 MHz. 

- Select bandwidth, Y and X axis spread selected to 0 and Y/X gain selected to 

minimum, and adjust the pre-amplification. 

- Position the probe at the center of the slot of the calibration block. 

- Adjust the spot position on the screen centre. 

- Select the filter and frequency of the filter. 

- Move the probe by screwing and unscrewing. Adjust X/Y gain to obtain 2 graduations 

of the screen. 

(4) Inspection of the thread of the rod 

(a) Visual inspection 

Any contamination of the surface that will impair Eddy current will be removed before 

inspection. If the removal is not possible, mark such discrepancies on the part for the 

later use during evaluation of Eddy current. 

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SERVICE BULLETIN 

(b) Eddy current inspection (see figures 2) 

(c) Position and screw the probe with the same scanning speed used during calibration 

operation until the end of the thread. 

(d) Evaluation of the indication 

Evaluate the indication by first resetting the sensitivity and recalibrating using the 

calibration block. 

(e) Acceptance criteria. (see flowchart paragraph 1.d (2)) 

Any readable indication with a deviation in a defect direction shall be cause of the 

rejection. Replacement of the rod before the next flight.

(f) Final operation ( Inspection report) 

On attached sheet paragraph “INFORMATION” note the indication intensity, the 

location and the calibration gain or the gain used for the evaluation if the gain defect 

is higher than the calibration defect. 

(5) Assemble the end fitting on the rod to restore the dimension L 2 (see figure 3), and test of 

the actuating cylinder, refer to CMM relevant to each actuating cylinder (see paragraph 

1.J). 

(6) Install the actuating cylinder on aircraft, Refer to airbus Service Bulletin A300-32-XXX. 

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Figure 1 

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Figure 2 

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Figure 3 

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BP 10 - 78142 Vélizy Cedex - France 

Tél: +33 (1) 46 29 18 00 - Fax: +33 (1) 46 29 87 70 

Télex: 634156F - Sita: QBHMDCR 

SERVICE BULLETIN 

NDT INSPECTION OF THE MLG ACTUATING CYLINDER

INFORMATION

AIRLINE AND A/C REGISTRATION No MSN. : ................. 

P/N OF THE MLG LEG : ................. 

S/N OF THE MLG LEG : ................. 

P/N OF THE MLG ACTUATING CYLINDER : ................. 

S/N OF THE MLG ACTUATING CYLINDER : ................. 

TOTAL CYCLES OF THE MLG ACTUATING CYLINDER : ................. 

P/N OF THE INSPECTED ROD : ............... 

S/N OF THE INSPECTED ROD : ............... 

CSN OF THE ROD : ............... 

RESULT

EDDY CURRENT INSPECTION : DEFECT YES ❏ NO ❏

INFORMATIONS

INDICATION INTENSITY:.................................................................................... 

LOCATION AND CALIBRATION GAIN:....................................................................... 

ACTION

RETURN THIS SHEET ASAP TO MESSIER-DOWTY SA PRODUCT SUPPORT 

ENGINEERING 

FAX 33 1 46298531 

October 27, 2005 Service Bulletin N° 470-32-806 

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