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My 1979 Cessna C421C Info Manual mentions Cowl Flaps as a checklist item with "(if installed)". I don't believe this Teledyne GTSIO-520-L engine includes cowl flaps. Does anybody know which models/engines do include cowl flaps? 

I suppose the A and/or B models. 

 

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Interesting as I was wondering this also last night when I noted that there were no cowl flaps on this bird.

1970-1975

Cessna 421B

Nose section extended 25 inches - Wing span increased by 2 feet - Landing gear beefed up - Several engine improvements: intercooler, oil cooler, turbocharger - Cowl flaps eliminated - Max takeoff weight increased 400 lbs. Landing weight increased by 700 lbs. - Cabin differential increased to 5 psi

https://www.twincessna.org/twin-cessna421.htm

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Does the "L" symbolize that it is liquid cooled?

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Posted (edited)

The Continental GTSIO-520-L and -N engines have one of the most efficient cooling of all General Aviation piston engines. Cylinder Head Temperatures rarely go up to 400 dF (limit 460 dF) even on climbs on hot days and without cowl flaps. Thus, the C421C does not have cowl flaps.

Indeed, I love those engines. Due to the reduction gear and the low prop RPM, the cabin is so quiet that normal conversation without headsets is easily possible.

I usually do cruise at 60 % MCP (30.3 in MP, 1700 RPM, 35.6 GPH), 217 KTAS at FL250 at mid cruising mass on an ISA day, cabin altitude 9,500 ft.

Edited by AndiKunzi
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