C-145 Crankshaft Question

[blueldr]

Del,

When ya get to the Motel 6, please turn out the light, will ya.

[n2582d]

If you cannot find any documentation on your crank installation, then you might consider having your engine inspected and it's logs revised to show that Mr. Johnsons STC was found to be installed, if your engine meets that crank PN, etc.. (i.e. dampered crank)

This discussion included many comments by myself and others of an anecdotal nature. My own comments mentioning the need to have the TIC170A STC as a basis of approval is actually not a simple matter, in your case. Why?
Because that STC specifies a certain series of propeller...which your modified engine does not utilize. In other words, your model "D" engine is not otherwise approved for a C-170, and our STC for installation of a "D" engine specifies a prop which has a 6-bolt hub....which your engine cannot use on it's 8-bolt crank.

This likely means a Field Approval or other basis will have to be found for your situation.

If you can't find previous approval for the modifications and engine/prop/spinner combination you have and if the STC that Ron has access to doesn't match your situation, here is what I would do. Assuming you don't have a generator larger than 35 amps on an undampered crank or that you have a dampered crank, I would use AC 43-210 and make the case that the O-300D engine case/8 bolt crankshaft/prop/spinner/airframe combination has been operating safely for X number of hours but with improper documentation. That should be all one needs to get a field approval. Here's what I wrote on this in 2008:

... I recently went through an IA renewal course online. On the subject of field approvals they talked about AC 43-210 which says,

"105. What are the two ways that an ASI may approve an alteration or repair?

a. Examination of data only (one aircraft). This is the most common kind of field approval. ... .

b. Physical inspection, demonstration, and testing (one aircraft). This field approval is typically used when:

(1) A major alteration or major repair has been made to the aircraft by a person or persons unknown and no substantiating approved data or maintenance record exists; or

NOTE: When an alteration or repair is made by person(s) unknown and without substantiating data, the mechanic or repair station may correct this discrepancy by creating a data package based on the installation and equipment already installed in the aircraft and submitting it to the ASI for approval. When it is approved, the ASI may inspect the aircraft. If the data package is acceptable, the ASI will sign in block 3 of FAA Form 337, approving the installation or repair based on his or her inspection or testing of the alteration or repair. If an alteration or repair is made that can be approved by a physical inspection or demonstration and testing, rather than just data, or if creating a data package is not practical, the ASI will perform the inspection and then sign off in block 3 of FAA Form 337.

(2) An alteration is installed, tested, and the ASI witnesses that test."

The course gave the example of an IA who when checking the records "finds that the (wrong model) engine has been in the airplane for 8 years and has 1100 hours on it -- this would be an example of an alteration that has been thouroughly flight tested. In a case like this testing would be complete and it would be just a matter of signing block 3 (of the 337 form) approving the alteration by physical testing."

[Bruce Fenstermacher]

George's explanation illustrates exactly why you may be better off converting your -D to a -A using M75-6R1. You have never answered whether or not you have an angle starter or not. If not this is a no brainer and the easiest paperwork wise.