AD 73-10-05

73-10-05 MCDONNELL DOUGLAS: Amdt. 39-1638. Applies to Model DC-10-10, DC-10-30, DC-10-30F and DC-10-40 airplanes.

Compliance required as follows unless already accomplished:

(A) Within 1200 hours time in service after the effective date of this AD, for those aircraft not operated in flight more than 30 minutes flight time to a landing at a suitable airport as defined in FAR 121.197.

(B) Within 300 hours time in service after the effective date of this AD, for those aircraft operated in flight more than 30 minutes flight time to a landing at a suitable airport as defined in FAR 121.197.

To prevent hydraulic fluid loss in the rudder standby power hydraulic system loops from inducing an additional failure in an adjacent second hydraulic system and to maintain flight control system margin capability, accomplish the following:

1. Install restrictors in the inlet to the motor side of the nonreversible motor pumps per McDonnell Douglas Service Bulletin 29-40, dated January 9, 1973, or later FAA-approved revisions or an equivalent modification approved by the Chief, Aircraft Engineering Division, FAA, Western Region.

2. Modify hydraulic piping in the 2-1 nonreversible motor pump system per McDonnell Douglas Service Bulletin 29-46, dated March 9, 1973, or later FAA-approved revisions or an equivalent modification approved by the Chief, Aircraft Engineering Division, FAA, Western Region.

3. In order to prevent nonreversible motor pump cavitation, install a system approved by the Chief, Aircraft Engineering Division, FAA, Western Region, to provide inflight capability to shut off hydraulic flow to motor side of the nonreversible motor pumps.

This amendment becomes effective May 15, 1973.