AD 82-22-01

82-22-01 BOEING: Amendment 39-4477. Applies to all Boeing Model 727 airplanes equipped with Decoto Leading Edge Actuators, P/N 10-61792-1, -2, -4, -5, -7, or -8. Compliance is required as specified in the body of this AD. To eliminate the possibility of inadvertent leading edge slat extension caused by fatigue failure of the Decoto leading edge actuator, accomplish at least one of the following four procedures prior to the accumulation of 30,000 landings on the actuator, or within the next 1500 landings, whichever comes later, unless already accomplished:

A. Perform a magnetic particle inspection of Decoto P/N 7-100433-1 actuator pistons in accordance with Boeing Service Bulletin 727-27-209 dated September 18, 1981. If a piston is not cracked it may remain in service provided it is reinspected at 15,000 landing intervals thereafter. If the part is cracked it must be discarded.

B. Replace the P/N 7-100433-1 piston with a redesigned piston P/N 7-100433-3. No repetitive inspections of replaced pistons are necessary--see NOTE after paragraph D, below.

C. Perform the leading edge hydraulic system internal leakage check per the 727 Maintenance Manual Chapter 29-00 procedures, as described in Boeing Service Bulletin 727-27- 209, Rev. 1, dated August 27, 1982. This leakage check must be repeated at intervals not to exceed 2400 landings. If the total leading edge system internal leakage exceeds 1000 cc/min, the additional acoustic or thermal procedures explained in the referenced service bulletin may be used to locate a specific defective actuator. If the total leading edge system internal leakage does not exceed 1000 cc/min, no further action is necessary until the next scheduled leakage . D. Rework existing uncracked P/N 7-100433-1 pistons per the Boeing approved procedure, which is described in Decoto Service Bulletin 27-109 dated July 23, 1981, and the referenced Boeing Service Bulletin. No repetitive inspections are required after rework for an additional service life of 40,000 landings. After accumulation of an additional 40,000 landings on the reworked piston, option B or C above must be incorporated.

NOTE: Replacement of the P/N 7-100433-1 piston with a redisigned piston P/N 7-100433-3, as described in option B above, constitutes terminating action for that particular actuator; no further inspections of that actuator are required. Replacement of all P/N 7-100433-1 pistons with P/N 7-100433-3 pistons on a given aircraft constitutes complete terminating action for this AD on that aircraft.

Alternate means of compliance with the AD which provide an equivalent level of safety may be used when approved by the Manager, Seattle Area Aircraft Certification Office, FAA Northwest Mountain Region.

Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate airplanes to a base for the accomplishment of inspections and/or modifications required by this AD.

This amendment becomes effective November 22, 1982.