80-07-03 CESSNA: Amendment 39-3723. Applies to the following Model R172K airplanes certificated in all categories:
(Serial Numbers R1722000 through R1723204, R1723206 through R1723211, R1723213, R1723214, R1723216 through R1723220, R1723222 through R1723226, R1723228 through R1723238, R1723240 through R1723246, R1723248 through R1723258, R1723260 through R1723272, R1723274 through R1723312, R1723314, R1723316 through R1723319, R1723321 through R1723329, R1723331 through R1723351, R1723353 through R1723362 airplanes).
COMPLIANCE: Required as indicated unless already accomplished.
To preclude failure of the engine oil pressure pump drive shaft and resulting oil pressure loss caused by an improperly installed tachometer shaft connector, within the next 10 hours' time- in-service after the effective date of this AD, accomplish the following in accordance with the applicable Cessna Service Manual:
A) Remove Cessna P/N 0550297-1 tachometer drive adapter assembly from the engine accessory case.
B) Using a five-eighths inch crow foot wrench, measure the breakaway torque of Cessna P/N 0550296-1 tachometer drive connector.
NOTE: Refer to Advisory Circular AC65-9A, Airframe & Powerplant Mechanics General Handbook, or Torque Wrench Manufacturers Instructions for formula for use of torque wrench with extensions.
C) If the breakaway torque is at least 200 inch-pounds and not over 350 inch- pounds, retorque the Cessna P/N 0550296-1 tachometer drive connector to 280 to 300 inch- pounds. Reinstall the tachometer drive adapter assembly and make the prescribed entry in the aircraft maintenance record indicating compliance with this AD.
D) If the breakaway torque is less than 200 inch-pounds or greater than 350 inch- pounds, prior to further flight, accomplish either of the following:
1. Replace the Teledyne Continental Motors P/N 634010 Oil Pump Drive Gear and P/N MS35756-1 Woodruff Key with a new Oil Pump Drive Gear and Woodruff Key of the same part number. (Refer to Teledyne Continental Motors Overhaul Manual for I0-360 Series Aircraft Engines for procedures.)
2. Perform a magnetic particle inspection of the Teledyne Continental Motors P/N 634010 Oil Pump Drive Gear in accordance with Section VI of the Teledyne Continental Motors Overhaul Manual for I0-360 Series Aircraft Engines. Give particular attention to the Woodruff Key slot and threaded area. If the oil pump drive gear is found cracked, replace with a new part of the same part number. Whether the oil pump drive gear is cracked or not, replace the P/N MS35756-1 Woodruff Key with a new part of the same part number. (Refer to Teledyne Continental Motors Overhaul Manual for I0-360 Series Aircraft Engines for procedures.)
E) Install the Cessna P/N 0550296-1 tachometer drive connector and torque to 280 to 300 inch-pounds. Reinstall the tachometer drive adapter assembly and make the prescribed entry in the aircraft maintenance record indicatingcompliance with this AD.
F) Airplanes may be flown in accordance with FAR 21.197 to a location where the maintenance required by this AD may be performed.
G) Any equivalent method of compliance with this AD must be approved by the Chief, Engineering and Manufacturing District Office, Federal Aviation Admin., Rm 238, Terminal Bldg. No. 2299, Mid-Continent Airport, Wichita, KS 67209.
This amendment becomes effective on March 31, 1980, to all persons except those to whom it has already been made effective by an airmail letter from the FAA dated March 13, 1980.