160 HP Upgrade

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Wasilla

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I was considering the 160 hp upgrade from 150 on my 1976 7GCBC. I see there is a Factory Bulletin saying that if you upgrade you need to upgrade to the metal wing spar too. Does everyone do the wing upgrade that has a 160? Does anyone have an explanation or know the logic behind it. Thanks!
 
The letter is based upon pre-existing approvals. Basically, it was easy to construct for people duplicating the modern 7GCAA. This includes the Approved Flight Manual which the FAA covets. The letter is really about a 'package deal' and not about a 10 HP upgrade.

You are adding less than 10% HP, it should not be much drama. You will want to talk to the FSDO though before you open your wallet.
 
I had the wings with metal spar installed on my aircraft due to other reasons than the 160 HP
However, after much soul searching and questioning, I had my engine upgraded to the 160 HP during an overhaul. My 1979 7GCBC operates on floats and I couldn't be happier with the 10 HP upgrade. Makes a big difference on take off. It gives you that nice warm fuzzy feeling on the smaller lakes.
Tom
 
I've been flying a 7GCB with a wood spar, the original no bounce gear, and a 160 HP engine. I never noticed anything special in the logs. I don't think it should be a problem, I'll dig deeper if you want.
 
Hi, I am an aspiring owner, though been flying a 7GCAA for several years. Currently looking at older one, 160HP upgrade, but without the metal spar. So I have similar questions. Love to hear more experienced folks view before I go too much further.

The engine was swapped for the 0320B2B, and in the logs it's stated that it was done based on "field approval". Later in its life, wood spars swapped out.

Two questions
A) I took a look at the champion service letter talking about upgrades to the 320B2B engine, and it explicitly states the need to go to the metal spar. It does restrict the age to 1974 -1980. The one I am looking at is 1965. So why wouldnt this recommendation apply backwards?
B) What does the logbook entry "field approval" mean?

This will be my first purchase, so,trying to make sure I understand all details before jumping in.

Thoughts appreciated?
 
jerrymjr said:
The letter is based upon pre-existing approvals. Basically, it was easy to construct for people duplicating the modern 7GCAA. This includes the Approved Flight Manual which the FAA covets. The letter is really about a 'package deal' and not about a 10 HP upgrade.

You are adding less than 10% HP, it should not be much drama. You will want to talk to the FSDO though before you open your wallet.
Click to expand...

This...again
Metal Spar retro aircraft after 1974 closely replicate current production (in crutial areas). Thus, the letter was not much of a stretch. As the airplane gets farther and farther away from current approvals, the more they need to be handled 'case by case'.
 
B) What does the logbook entry "field approval" mean?

Field Approval means that it was not done under an STC (Supplimental type certificate) nor was it listed on the TCDS (Type Certificate datta sheet). So the Appoval was from an FAA inspector, there must be a form 337 (Major repair and alteration) in the aircraft paperwork, it has the details of the "FieldApproval".
 
As the upgrade is within 10%, the FAA said it is OK. The FAA said it will reject the field approval request and send a letter stating that no field approval is needed as it is within 10% in the upgrade to the 160. 1976 7GCBC with an O-320A2D.

Thanks for all the responses!
 
That is not true here in Socal at LAX FSDO. The 160hp MAY be field approved because it is with 10%, anything above 10% must be STC's and is no longer allowed to be field approved, I can provide the FSDO guidance link when I get home that spells this out. Any engine that isn't on the type certificate for your airplane needs a Form 337 and approval.
 
I still have the original engine, it's still an A2D. Only difference is that it is bumped up 10 HP from 150.

Thanks for the reference, quite a read. From what I can tell on page 28, is that the engine would be eligible for field approval if there was "support" from the DER, the ODA, or the ACO.

Thanks for the comments.
 
That's exactly it. If you go more than a 10% increase, you have to have an STC. I know all this because I'm working on making my '70 into a B2B powered 160 HP.
 
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