AD 77-08-03

77-08-03 GRUMMAN AMERICAN AVIATION CORPORATION: Amendment 39- 2873. Applies to Model AA-5A, serials AA5A-0001 through AA5A-0340 and Model AA-5B, serials AA5B-0001 through AA5B-0451 airplanes equipped with an alternate static source system.

Compliance required prior to further flight under Instrument Flight Rules (IFR) or night flight, or within the next 25 hours day Visual Flight Rules (VFR) time in service after the effective date of this AD or the next scheduled inspection, whichever comes first, unless already accomplished.

To prevent faulty altitude, airspeed, and vertical speed indications from being presented to the pilot, accomplish the following: Disassemble, clean, lubricate, and reassemble the alternate static source valve, Gerdes part number A-1390, and leak test the static system in accordance with the following procedure:

1. Remove static source valve knob and jamb nut. 2. Note static line routing and remove lines from valve body. 3. Remove attach screws and valve assembly from aircraft. 4. Disassemble valve by removing hex bushing from forward end of valve and pushing valve shaft thru valve body. 5. Wipe and save all grease from valve shaft with a clean lint-free cloth. 6. Clean inside valve body with a lint-free cloth. 7. Blow compressed air thru fittings into valve body to clear ports. 8. Reclean inside of valve body. 9. Lubricate O-rings only with a very thin film of grease removed in Step 5. Keep rest of shaft dry.

10. Reassemble valve, mark serial number plate with a red dot, reinstall in instrument panel and reconnect lines to their respective ports.

11. Conduct a static system leak test according to the procedure in Grumman American Service Bulletin No. 160, dated March 21, 1977, or FAA Advisory Circular AC 43- 203A (Ref. FAR 23.1325).

Any equivalent method of compliance with this AD must be approved by the Chief, Engineering and Manufacturing Branch, FAA, Southern Region.

This amendment becomes effective April 19, 1977.