ron74887 wrote:...The reason for the STC was the prop not (t)he engines si(n)ce they were identical in every operating aspect. The prop was never approved for the 170 however it was for the 172 therefore no need to cover the 172, ... Ron
Ron (joking here) ... the new EM prop is also "identical in every operating aspect".... so why the STC?
It makes absolutely no difference what the operating similarities may or may not be. The problem is that the specific engine model, and prop model, are
not approved for the 170. And it makes no difference if it's only the prop, or only the engine (you can't install one without the other without some heavy-duty welding)....
... since the later engine uses a 6 bolt prop flange in lieu of the earlier 8 bolt design. In any case... it's not the operating similarities that make an approval basis necessary. It's the model designation differences....and the un-approved basis of those changes.
To all: Ron and myself (and others) have had several discussions on this matter to whit:
Ron pursued this development of this STC in order to achieve the use of the EM prop on the 170, and this STC accomodated that purpose.
Some FAA inspectors.... (hold onto your helmets...this is really gonna surprise you).... don't know their props from their engines.... And I suspect that such an inspector was involved in the 172/prop situation Ron just attempted to describe. (If anyone can sift through that earlier msg.)
Despite that goofy inspector's even goofier opinion,... the majority of FAA Inspectors do not hold the same view. The majority of them hold the view that in order to install a C or D engine in a 170, that an STC or other basis of approval must be used for the purpose. That is the real value of Ron's STC. Repeat: According to the prodominant view at FAA, you may not install a C or D engine...or it's 6-bolt prop...in a 170 without a basis of approval...which Ron's (now TIC170A's) STC covers.
The STC does not apply (in it's current version, and in accordance with the predominant FAA view) to Cessna 172's.
Just because you can get ONE inspector to sign off on something does not make it valid.
I'll give you an example: My
C170B, N146YS
It left the factory for South America in 1952/53 with an O-300-A and MDM-7653 prop. It never had a U.S. Airworthiness Certificate and it spent two decades flying/sitting around El Salvador. It re-entered the US in the early 70's with an O-300-C and an EM-7655 prop. The FAA inspected the airplane for conformity with the type certificate (which applies to all 170's...and does not apply to 172's)... TCDS A-799, and it was
incorrectly issued a new Standard Airworthiness Certificate. Although the FAA themselves reviewed the aircraft and it's records...it did not meet it's type certificate because it had an engine and prop that was not authorized. It made no difference that it was the FAA's own Inspector missed that tidbit. The result is the same...the airplane was not legal to fly in the U.S.
The airplane remained with that Airworthiness Certificate and no one caught the error or took corrective action upon it until it's restorer filled out a Form 337 which quoted
another aircraft's Form 337 having a "field approval" (Block 3 approved by FAA.) Note: This merely documented the incorrect engine/prop. It did not make N146YS legal, because the new 337 for N146YS did not have Block 3 approved. I bought the airplane in 2000 knowing this issue existed.
I was faced with either continuing to operate the aircraft without it's documentation being legalized (and risking some FAA type somewhere grounding my airplane by revoking it's improperly-issued Airworthiness Certificate when they discovered the error), or going to the expense of re-converting the airplane back to it's original condition (..didn't want to do that since it had a 200-hour O-300-C and EM prop in it.) Needless to say, anyone who ever considered buying it from me would beat me down on price over this issue. (And I strongly suspect that's why I got the airplane favorably priced to me, ....because the restorer was frustrated by other potential purchasers.... and he had the airplane in the DAL FSDO region which had a reputation of "NO!"..when it came to any kind of field approvals.)
I had the decision to make as to how to make my illegal airplane meet the FARs. I contacted FAA-FSDO in San Antonio, OKC, and FTW and they all agreed that the airplane did not meet it's type certificate, and therefore was not technically legal for operation on the Standard Airworthiness Certificate which it had been issued improperly by their own inspector way back in the early 70's. The restorer did not agree with them, but that isn't what counts in my view, or in the FAA's. FAA took the position that I must either obtain proper field approval, or I must acquire an STC covering this alteration of the aircraft's original design.
I was under the process of obtaining my own "field approval" under the more challenging new rules, when (at the New Orleans mid-year board meeting) I became aware that past president Ron Massicot had such an STC which already covers this issue.
Summary: Despite the original intent of the STC, it's actual effect is to provide a legal method of installing an O-300- C or D engine and associated prop in a Cessna 170, 170A, or 170B. Unless further development and approval is made for it, any other use of the STC will likely be in the imagination of a mis-informed inspector. (Well, in accordance with past-prez Ron Massicot..."further development" has been found....already in accidental oversight...and if correct, the STC will apply to 172 aircraft. The queston I now have is: Which models 172?)
So now It is FACT that the STC covers the 172. I was sending the transfer letter and with that the copy of thee approved ammendments to be sure they were included since they did not reissue the front page--finding that I reread the letter 