AD 72-23-03

72-23-03 CESSNA: Amdt. 39-1551. Applies to Models 336 (Serial Numbers 336-0001 thru 336-0195) and 337 (Serial Numbers 337-0001 thru 337-0239) airplanes.

Compliance: Required as indicated, unless already accomplished.

To prevent inadvertent retraction of wing flap and to insure positive operation of the electrical wing flap actuators, accomplish the following:

A) On all aircraft with more than 100 hours' time in service, within the next 25 hours' time in service after the effective date of this AD, unless already accomplished within the previous 75 hours' time in service, and thereafter at intervals not to exceed 100 hours' time in service, visually inspect the actuator jack screw for condition of lubricant and presence of contamination and scale in accordance with the procedure described in Cessna Service Letter SE70-16, Supplement 1, dated July 10, 1970, or later FAA-approved revision. If any of the conditions prescribed in the inspection criteria are noted, prior to further flight, remove, clean and relubricate the actuator jack screw in accordance with Cessna Service Letter SE70-16, dated June 12, 1970, or later FAA-approved revision, or any equivalent procedure approved by the Chief, Engineering and Manufacturing Branch, FAA, Central Region.

B) On all aircraft with more than 500 hours' time in service, within the next 25 hours' time in service after the effective date of this AD, unless already accomplished within the previous 75 hours' time in service, remove, clean and relubricate the actuator jack screw in accordance with the procedure described in Cessna Service Letter SE70-16, dated June 12, 1970, or later FAA-approved revision, or any equivalent procedure approved by Chief, Engineering and Manufacturing Branch, FAA, Central Region.

C) In addition, on all aircraft at each annual inspection, or at intervals not to exceed 12 months, whichever occurs first, remove, clean and relubricate the actuator jack screw in accordance withthe procedure described in Cessna Service Letter SE70-16, dated June 12, 1970, or later FAA-approved revision or any equivalent procedure approved by Chief, Engineering and Manufacturing Branch, FAA, Central Region.

NOTE: Cessna Service Letter SE70-16, Supplement 2, dated August 28, 1970, specified some brand names of Molybdenum Disfulfide Grease.

D) On or before April 1, 1973, modify the aircraft in accordance with Cessna Service Letter ME72-19, dated October 6, 1972, or later revisions. Equivalent methods of compliance with this paragraph must be approved by Chief, Engineering and Manufacturing Branch, FAA Central Region.

E) Upon compliance with Paragraph D, the requirements of Paragraphs A, B, and C are no longer applicable.

NOTE: The agency recommends that the procedures for maintaining the flap system as specified in applicable Cessna Service Manuals be followed.

This amendment becomes effective November 10, 1972.