AD 63-23-02

63-23-02 LYCOMING: As amended by Amendment 39-627 - is corrected as follows: Applies to all O-320 type engines which incorporate the 7/16" diameter exhaust valve stem with camshaft assembly P/N 68769.

Compliance with (d) required at the times indicated in (a), (b), or (c) as applicable.

(a) Engines used for aerial dusting or chemical application service since new or since replacement of all exhaust valves and valve guides.

(1) As of the effective date of this AD, engines with more than 200 hours' time in service since new or since replacement of all exhaust valves and valve guides, shall comply within the next 100 hours' time in service and every 300 hours' time in service thereafter.

(2) As of the effective date of this AD, engines with 200 hours' or less time in service since new or since replacement of all exhaust valves and valve guides, shall comply prior to the accumulation of 300 hours' time in service since new or since exhaust valve and valve guidereplacement and every 300 hours' time in service thereafter.

(b) Engines used in all operations other than those covered in paragraph (a).

(1) New engines and engines which have a record of at least No. 3 and No. 4 exhaust valve and valve guide replacement.

(i) As of the effective date of this AD, engines with more than 400 hours' time in service since new or since the replacement of No. 3 and No. 4 exhaust valves and valve guides, shall comply within the next 100 hours' time in service and every 500 hours' time in service thereafter.

(ii) As of the effective date of this AD, engines with 400 hours' or less time in service since new or since replacement of No. 3 and No. 4 exhaust valves and valve guides shall comply prior to the accumulation of 500 hours' time in service since new or since No. 3 and No. 4 exhaust valve and valve guide replacement and every 500 hours' time in service thereafter.

(2) Engines which have a record of exhaust valve replacement of at least No. 3 and No. 4 valves but no record of valve guide replacement.

(i) As of the effective date of this AD, engines with more than 200 hours' time in service since replacement of No. 3 and No. 4 exhaust valves shall comply within the next 100 hours' time in service and every 500 hours' time in service thereafter.

(ii) As of the effective date of this AD, engines with 200 hours' or less time in service since replacement of No. 3 and No. 4 exhaust valves shall comply prior to the accumulation of 300 hours' time in service since exhaust valve replacement and every 500 hours' time in service thereafter.

(c) Engines whose usage is changed between inspections.

(1) Engines whose usage is changed from that specified in (a) to that specified in (b) will comply as originally required in (a) for the first inspection after usage change. Subsequent inspections will be as required in (b).

(2) Engines whose usage is changed from that specified in (b)to that specified in (a) will comply with the requirements of (a) for the first inspection after usage change and for subsequent inspections.

(d) Inspect and, where necessary, replace exhaust valves and guides in accordance with Lycoming Service Bulletin No. 293B or other alternative method approved by the Chief, Engineering and Manufacturing Branch of the Eastern Region.

This amendment is effective Dec. 9, 1963.

Revised August 6, 1968.