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63-23-02: Exhaust Valves

FAA order 63-23-02 is an airworthiness directive in force since August 6, 1968. The FAA's subject line: Exhaust Valves. It names the Lycoming O-320-A1A, Lycoming O-320-A1B, Lycoming O-320-A2A, Lycoming O-320-A2B, Lycoming O-320-A2C, Lycoming O-320-A3A, Lycoming O-320-A3B, Lycoming O-320-A3C, Lycoming O-320-B1A, Lycoming O-320-B1B, Lycoming O-320-B2A, Lycoming O-320-B2B, Lycoming O-320-B2C, Lycoming O-320-B3B, Lycoming O-320-C2A, Lycoming O-320-C3B, Lycoming O-320-D1A, Lycoming O-320-D2A, Lycoming O-320-D2B, Lycoming O-320-E1A, Lycoming O-320-E2A, Lycoming O-320-E2B, Lycoming O-320 series engines: about 28,057 aircraft on the U.S. register today across them, though an order usually covers particular versions or serial numbers rather than every one. System: engine.

What it applies to as the FAA lists it

Kind of product: Engine
Makes: Lycoming Engines
Models: O-320-A1A, O-320-A1B, O-320-A2A, O-320-A2B, O-320-A2C, O-320-A3A, O-320-A3B, O-320-A3C, O-320-B1A, O-320-B1B, O-320-B2A, O-320-B2B, O-320-B2C, O-320-B3A, O-320-B3B, O-320-B3C, O-320-C2A, O-320-C2B, O-320-C3A, O-320-C3B, O-320-D1A, O-320-D1B, O-320-D2A, O-320-D2B, O-320-E1A, O-320-E1B, O-320-E2A, O-320-E2B
Engine series: Lycoming O-320-A1A 21 aircraft
Lycoming O-320-A1B 2 aircraft
Lycoming O-320-A2A 9 aircraft
Lycoming O-320-A2B 179 aircraft
Lycoming O-320-A2C 1 aircraft
Lycoming O-320-A3A 5 aircraft
Lycoming O-320-A3B 12 aircraft
Lycoming O-320-A3C 1 aircraft
Lycoming O-320-B1A 17 aircraft
Lycoming O-320-B1B 3 aircraft
Lycoming O-320-B2A 11 aircraft
Lycoming O-320-B2B 92 aircraft
Lycoming O-320-B2C 55 aircraft
Lycoming O-320-B3B 22 aircraft
Lycoming O-320-C2A 2 aircraft
Lycoming O-320-C3B 1 aircraft
Lycoming O-320-D1A 116 aircraft
Lycoming O-320-D2A 72 aircraft
Lycoming O-320-D2B 18 aircraft
Lycoming O-320-E1A 3 aircraft
Lycoming O-320-E2A 99 aircraft
Lycoming O-320-E2B 4 aircraft
Lycoming O-320 series 27,312 aircraft

Dates and paperwork

In force since: August 6, 1968
Docket: Unknown
Status: Current
The FAA's document: Read the order on the FAA's site

The order itself the regulatory text, as published

Show the full text (3,421 characters)

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.

Source: FAA Dynamic Regulatory System, airworthiness directives. The FAA's document is the authority; the register counts are this site's, from the FAA register of November 2, 2026. Connections as data: /graph/directive/63-23-02.json · aircraft systems.