AD/INST/29 - Bendix M-4 (A,B,C,D) Automatic Flight Control System Servo - Inspection and Modification (Cth)

COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 107 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES

Instruments and Automatic Pilots

AD/INST/29 Bendix M-4 (A,B,C,D) Automatic Flight Control System Servo - Inspection and Modification

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Applicability: All Models 3013E, 3013F, 3013G, 3013H, 3013J and 3013K Primary Servos (part numbers and serial numbers listed below) delivered, repaired or overhauled after 1 January 1979 that do not contain Modification Number 4.

Primary Servo Model Number Primary Servo Part Number Primary Servo Serial Number *3013E 1U014-01 Any primary servo that has had magnetic clutches (P/N 717503- 0001) installed after 1 January 1979. *3013F 1U014-02

*3013G 1U014-03 3013H 4000523-8501 9530 thru 9925 and any primary servo that has been repaired or overhauled after 1 January 1979. 3013J 4009506-8501 1775 thru 1792 and any primary servo that has been repaired or overhauled after 1 January 1979. 3013K 4009506-8502 2067 thru 2110 and any primary servo that has been repaired or overhauled after 1 January 1979.

*Older model primary servos which may contain magnetic clutches manufactured by Bendix.

Document: Bendix Alert SB M-4D-060.

Compliance: Within 100 hours time in service after 31 January 1981.

Background: Instances have been reported overseas of mechanical seizure of the primary servo motors detailed above. When this condition exists the primary flight controls may be subjected to an increase in required actuation forces which may reach the slipping value of the capstan torque limiters, thus demanding greater effort by the pilot. The seizure may occur whether the autopilot is turned on or off.