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Approval for C90-8 on a J3 C65

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D

Denton

Guest
As John T said earlier, it’s in the TC.

SPECIFICATIONS PERTINENT TO ALL MODELS (Cont.) Engines and Engine Accessories - Fuel and Oil System (311)(C) (Cont.)

(10) C-90-8F (landplane, skiplane and seaplane) Use actual weight change Engine Limits: Takeoff, 2475 r.p.m. (90 hp) All other operations, 2375 r.p.m. (80 hp) Fuel: 80 minimum octane aviation gasoline Oil Capacity 5 qts. Propeller Limits: Static r.p.m. (with Item 101, 5 or 6 propellers) at maximum permissible throttle setting: Not over 2300; not under 1950 for land and skiplane, and not under 2100 for seaplane. No additional tolerance permitted. Diameter: (a) With Item 5 or 6 propellers: Not over 71 inches, not under 69.5 inches. (b) With Item 101 propeller: Not over 76 inches, not under 70 inches. Carburetor heat system must be modified to provide required heat rise. Approved modification made by M. Mullis, York, South Carolina.

My Input.
If you take a C90-12, and remove the rear case, and install the no starter type rear cover, then it can be installed as per. Above.
The FAA FSDO said, it would be best to simply fill out a 337 for Field Approval for the change to the rear case cover, (cast or plate type) and install the engine as
Per. 311 (C )(10), This 337 may not really be required, but when in doubt, fill out a 337.

I just thought this was interesting.
By the way, I just got off the phone with the Oklahoma FAA, and he said that under the FAA Inspectors Handbook (part something) You can install a larger engine on any aircraft, with only a Field Approval, as long as it does not exceed a 10% increase in HP.

 

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