Why did GAMI need an STC?

[peter-h]

Any set of GAMI-matched injectors is potentially identical to a random injector set which came with the original engine.

You could fill a bucket with old Lyco injectors, and every time you close your eyes and stick your hand in the bucket and pull out four or six of them, the set you pulled out will be a perfect GAMI-matched set for somebody's engine out there.

So, why the STC?

Part 43 Appendix A lists the Major Mods and this cannot possibly be a Major Mod. And the injectors need to be fitted by an A&P anyway.

 

[Doggtyred]

"The FAA advised GAMI that any alteration of the fuel injector specifications would not be legal unless it was done under an STC."

http://www.gami.com/gamijectors/gamijectors.php

When the 800 lb gorilla (who also makes and enforces the rules) says you have to have an STC, you get the STC.

 

[peter-h]

The site says

The FAA advised GAMI that any alteration of the fuel injector specifications would not be legal unless it was done under an STC.

but are GAMI changing the fuel injector specifications?

AIUI, any GAMI injector is within the original flow spec.

If GAMI open out any injectors outside the original flow spec, then I understand the STC.

 

[kgruber]

One reason is each GAMInjector is required to be installed in a particular cylinder, and has a part number exclusive to that engine's requirements.

Stock go anywhere.

 

[John Collins]

The site says

The FAA advised GAMI that any alteration of the fuel injector specifications would not be legal unless it was done under an STC.

but are GAMI changing the fuel injector specifications?

AIUI, any GAMI injector is within the original flow spec.

If GAMI open out any injectors outside the original flow spec, then I understand the STC.

The Gami injectors may be within the specification, but they are precision tuned to the cylinder they are installed in. They specify which cylinder the injector must be installed in, whereas the off the shelf injectors can go in any cylinder. The whole point of the Gamijector is to eliminate any imbalances in the fuel delivered to each cylinder so that the engine will run smoothly when lean of peak.

In the case of the Lycoming engine the fuel injection system starts out much better balanced than the TCM IO470, IO520BA-BB and IO550B that are very unbalanced due to the runner induction system that unintentionally transports fuel from the rear cylinders to the forward ones.