(Dan Thomas)
shared these priceless pearls of wisdom:


- I assumed a typo right off, since I knew of no 4552 in any 172s.

Neither did I, but there are some really goosey things done in the name of STC,
and when he said that he had a non-stock STCd engine, I figured that perhaps
they wanted a heavier filament for vibration, or that there was some subchapter
footnote that said that engines of such and such a horsepower needed a brighter
lamp... I didn't question the bulb, since the 4552 DOES cross to an aircraft
landing light bulb.

-
- And after Jim Weir razzed me, I doublechecked the Cessna parts
-manual again, and for a whole serial number range they call for a 4522
-bulb on a 20 amp breaker. They DO make mistakes sometimes.

To which I abjectly apologize. However, "they" was all the way up the chain of
command, from the design engineer to the chief engineer to the certifying FAA
office to...with no subsequent AD to replace the breaker AND the wire or replace
the bulb with a 100-watter.

The person with the original question is now in somewhat of a dilemma. Replace
the wire and breaker on a 337 (yes, I *do* consider this a major change) or
replace the bulb on a 337 (again...) or do either one and just shutta uppa da
mout'.

Yer choice. I know mine.

Jim
Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com