Carb to FI: Do I need Phase I Again

[lr172]

I am thinking of swapping my O-320 Carb for a Bendix FI setup. Is that considered a Major alteration requiring me to do 5 hours of Phase I? I am curious how other interpret this change.

Larry

[luv2flypilot]

I am also curious about this as its something I may also do in the future with my O-360. It may be close to an additional 5 lbs with the additional boost pump, injectors, fuel distributor, fuel lines, and swap out of carburetor to throttle body. If its more than 5 lbs, I believe it would be required to go back into Phase I for 5 hours with updated limitations provided by your local FSDO office. I would consider it a major change, however others may not agree its not a new prop or new engine.

[rvbuilder2002]

Check out THIS thread

Question was regarding changing props, but it applies the same here.

In your case.... my opinion is that it is a major change.
At the very least, in the context of reliability.

There are a lot of system related things that potentially will be changed when you switch to fuel injection (new hoses, pumps, lines, controls, etc.) that could all have an influence on reliability.

[Toobuilder]

I should know better than to open this can of worms...

I believe the main point of the test period is "test". That is, have the flying or operating characteristics been vetted? Does it stall funny, did the ROC change, is there some new procedure required to operate the aircraft, etc. You are not going to get any useful "reliability" data from a 5 hour trip through Phase 1 - not any more than the typical and expected functional test flight that we all do (or should be doing) following maintenance.

Let the fireworks begin...

[lr172]

Originally Posted by Toobuilder

I should know better than to open this can of worms...

I believe the main point of the test period is "test". That is, have the flying or operating characteristics been vetted? Does it stall funny, did the ROC change, is there some new procedure required to operate the aircraft, etc. You are not going to get any useful "reliability" data from a 5 hour trip through Phase 1 - not any more than the typical and expected functional test flight that we all do (or should be doing) following maintenance.

Let the fireworks begin...

So, I completely agree with this. Clearly some test flights are necessary for any swap like this, but a redo of Phase I is ridiculous for the proposed change, as it should have no impact on the performance of the aircraft, short of not performing as designed or improper installation. I understand things like props that will change the behavior and performance of aircraft and it's handling.

I assume the intent of the requirement is to test only the unique aspects of the modification and hence the shorter test period . I was looking more to the obligation, not the necessity. I never look for logic or reason in anything regulatory. I am obligated to do Phase I testing for "Major" modifications. I am looking to see how the FAA interprets "Major" modifications and how other have interpreted this definition.

Larry

[rvbuilder2002]

Originally Posted by Toobuilder

You are not going to get any useful "reliability" data from a 5 hour trip through Phase 1 - not any more than the typical and expected functional test flight that we all do (or should be doing) following maintenance.

I disagree (but not launching any fireworks).

Will it vet the long term durability of the installation? No.

But neither does a 25 or 40 hr Phase One test period.
Any experienced RV builder knows that 100 + hours is when durability issues more often start to show up.

But it might (note I said "might".... nothing is an absolute) vet things like hose or line fittings that were not fully tightened (fuel leaks....), engine controls that aren't properly rigged (wont go full rich or full throttle, etc.)

[rvbuilder2002]

Originally Posted by lr172

I am looking to see how the FAA interprets "Major" modifications and how other have interpreted this definition.

The thread I linked to in my previous post quotes what the FAA's definition of a major change is Click on the THIS to go to that thread.

BTW, my opinion of it being a major change does not mean I think you have to repeat a full Phase one test period (25 or 40 hrs). The standard is 5 as you wrote in your original post. The primary requirement is what ever the operating limitations for your specific aircraft say. Some operating limitations require notification of the local FSDO before flying after incorporating any major change (yes, you have to decide whether by their definition its is or not).

[gasman]

Originally Posted by lr172

I assume the intent of the requirement is to test only the unique aspects of the modification and hence the shorter test period . I was looking more to the obligation, not the necessity. I never look for logic or reason in anything regulatory. I am obligated to do Phase I testing for "Major" modifications. I am looking to see how the FAA interprets "Major" modifications and how other have interpreted this definition.

Larry

And then you will have your answer.

My guess is this is a major modification to the fuel system that is a major system to the aircraft.

[Toobuilder]

Originally Posted by gasman

My guess is this is a major modification to the fuel system that is a major system to the aircraft.

That's really the rub. There are some very specific items that are automatically in the "major" category, but when you have to interpret the non specified items and look at the normal criteria of "CG change, operating characteristics, pilot interface, performance, etc...", then the arm chair lawyers have a go.

Example: Changing from a magneto to EI - EAA says "no" to a major change (and I agree), yet if you call 20 different FSDO's you will get 25 different answers.

[lr172]

Originally Posted by Toobuilder

Example: Changing from a magneto to EI - EAA says "no" to a major change (and I agree), yet if you call 20 different FSDO's you will get 25 different answers.

I can't see how changing a carb to FI is any more or less major than changing a Mag to EI. My challenge here is that my opinion isn't really relevant.

Any maintenance is risky and it seems to me that these types of changes should be dealt with like other risky maintenance requiring test flights and sign-offs, not Phase I testing. Replacing a failed fuel pump can cause just as much damage as what I am proposing. Let me go a step further. I can take the engine out, strip every part off of it, send all the parts to countless different suppliers. Re-assemble all of the parts, with or without appropriate skill and experience. Some parts new, some re-used, some re-worked. Enormous opportunity for problems to appear and no Phase I required as it is Maintenance and not an Alteration.

I truly believe the spirit of the regulation is for alterations impacting flight and performance characteristics, not for the swapping of version A part to Version B part on the engine. If I alter the design of my wing tips, Clearly I need an abbreviated Phase I period to shake it out and run it through the critical tests . Unfortunately all that matters is how the FAA views things when the @$#% hits the fan and herein lies the problem, no real way to get that guidance.

Sorry for the rant here. I"ll stop now and read the post recommended by RVBuilder above. Thanks to all for your input.

Larry