AD 72-20-02

72-20-02 CONTINENTAL: Amendment 39-1522 as amended by Amendment 39-1613 as amended by Amendment 39-1774 is further amended by Amendment 39-1974. Applies to Models IO-470-D, IO-470-E, IO- 470-F, IO-470-H, IO-470-L, IO-470-M, IO-470-N, IO-470-S, IO-470-U, IO-470-V, and TSIO-470-B, TSIO-470- C, TSIO-470-D engines which have installed "Non-H" cylinder assemblies, Part Number 626820, and "H" cylinder assemblies manufactured or remanufactured prior to April 1963. NOTE 1: "H" type cylinders are those having the letter H impression stamped on the top edge of the rocker box flange over the exhaust valve. "Non-H" type cylinders do not have this identification. Compliance: Required as indicated unless already accomplished. To preclude additional inflight failures of Part Number 626820 "Non-H" type cylinder assemblies and "H" type cylinder assemblies manufactured or remanufactured prior to April 1963, accomplish the following or an equivalent procedure approved by the Chief, Engineering and Manufacturing Branch, Southern Region, Atlanta, Georgia: A. Within the next 20 hours' time in service after the effective date of this airworthiness directive and thereafter at intervals not exceeding 20 hours' time in service from the last inspection: (1) Visually inspect the circumference of these cylinder assemblies at the junction of the aluminum head and steel barrel for oil leaks and/or combustion product stains. Engine permanent maintenance record entry must be made to reflect airworthiness directive compliance. NOTE 2: In order to perform the inspection required by Paragraph A(1) of this airworthiness directive, it may be necessary to remove engine cowling or access doors to permit visual examination with mirrors or other visual aids of the prescribed area of the cylinder. If the engine is clean and free of oil in the area to be inspected, the inspection required by Paragraph A(1) may be performed without further cleaning of the engine. If oil leakage froman unknown source has caused a generally oily condition, the engine should be washed down and run up to normal operating conditions prior to the inspection required by Paragraph A(1). During the inspection it may also be helpful to rotate the propeller to detect significant differences in compression between cylinders or audible compression leakage through a crack in the cylinder barrel. (2) The inspection(s) required by Paragraph A(1) must be performed by those persons authorized to perform inspections under Federal Aviation Regulation 43.3 except that on aircraft not utilized in air carrier services the inspection(s) may be performed by the holder of a pilot's certificate issued under Part 61 of the Federal Aviation Regulations on any aircraft owned or operated by him. (3) If oil leaks and /or combustion product stains are found at the junction of the cylinder head and barrel during any inspection required by Paragraph A(1), before further flight, a certificated powerplantmechanic shall investigate and establish the source of these conditions. If a cylinder barrel crack is found, the cracked cylinder must be replaced with an airworthy part. B. At next engine overhaul replace Part Number 626820 "Non-H" cylinder assemblies and "H" cylinder assemblies manufactured or remanufactured prior to April 1963 (as identified by the date of manufacture impression stamped in the machined area beneath the valve rocker shaft supports) with Part Number 626820 cylinder assemblies manufactured or remanufactured after April 1963 and having the letter "H" impression stamped on the top edge of the rocker box flange over the exhaust valve. NOTE 3: On engines manufactured or remanufactured by Teledyne Continental Motors during 1964 or later, as indicated by the year suffix on the serial number, it may be assumed without further verification that "H" type cylinders installed were manufactured subsequent to April 1963 if maintenance records do not indicate a cylinder exchange. On other engines having "H" type cylinders installed, it will be necessary to establish the cylinder's date of manufacture by removing the rocker box cover and inspecting the area beneath the rocker arm for the impression stamped manufacture date. Information on the location of this stamp was given on Page 115 of the August 1971 General Aviation Inspection Aids Summary. However, in the event the manufacture date appears ambiguous or illegible Teledyne Continental Service Bulletin M73-2 should be used to identify cylinders. NOTE 4: The term "Overhaul" as used in this AD is taken to include both major and top overhaul. When considering top overhauls, the AD applies equally to individual cylinder top overhauls as well as a complete engine assembly. C. Inspections as outlined in Paragraph A(1) are no longer required when Paragraph B has been accomplished. This airworthiness directive Amendment 39-1522 supersedes Amendment 39-509, AD 67-31-5. Amendment 39-1522 became effective September 25, 1972. Amendment 39-1613 became effective April 2, 1973. Amendment 39-1774 became effective February 1, 1974. This Amendment 39-1974 becomes effective October 2, 1974.