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Carb to FI: Do I need Phase I Again

lr172

Well Known Member
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
 
Carb to EFI Upgrade

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.
 
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.
 
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...
 
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
 
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.)
 
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).
 
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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.
 
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.
 
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
 
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Ok, I read the recommended post. Here is the key language of Major (i.e. not minor) change:

A ??minor change?? is one that has no appreciable
effect on the weight, balance,
structural strength, reliability, operational
characteristics, or other characteristics
affecting the airworthiness
of the product. All other changes are
??major changes?? (except as provided in
paragraph (b) of this section).


The only category that seems applicable is "Reliability," as the engine and plane should perform the same as before the change (W&B should not be considered appreciable as it will only be a couple of pounds). I don't see how the FI could be considered a reliability change. 10 of 1,000's of Lycoming engines have proven a pretty similar reliability track record for both. I can't imagine that changing from one sub-version of MA 4SPA to another would be any more major of a change than a change from carb to FI. The engine fundamentally performs the same either way. I could argue that changing to a different heat range spark plug is no less major than going from a proven carb to a proven FI (I will be using the tried and true Bendix setup).

I guess my real question is, does my interpretation count for anything.

Larry
 
I guess my real question is, does my interpretation count for anything.
Larry

In reality, it is the only one that counts (as long as there was no incident that resulted in an investigation in the first few flight hrs after the modification).

You will be the one doing the work and I presume doing the return to service log book entry. So you hold the responsibility of deciding whether just doing a short post work test flight meets the requirements of your operating limitations based on the FAA's definition of a major change.

It sounds like you have made that decision.
 
If one takes a few minutes to peruse the Experimental Aircraft accident history, one will find a large proportion of accidents have happened in the "new airplane" phase. Further investigation will reveal that, of these "new airplane" accidents, a startling proportion of the airplanes came to grief as a result of fuel delivery problems.

With this in mind, irrespective of regulatory requirements, the number one driving factor here has to be flight safety. Changing the fuel delivery system will mean changing a large number of components in the fuel delivery chain. Any one of the new components could introduce a flaw which ultimately would result in engine stoppage. From this perspective, it would seem prudent to voluntarily enter a formal flight test regime, with the usual limitations on passenger carrying and distance from home field. Whether this is formally documented as a return to Phase 1 or not can be debated until the cows come home - your grieving family won't care about the regulations. The only thing that really matters is that you ensure your safety and the safety of others isn't compromised.

With respect to the wording of the regulation, installation of fuel injection will require the removal of a cockpit control (carb heat) and perhaps installation of new cockpit controls, plus introduction of new procedures for starting, running and re-starting the engine. One could easily and logically argue this modification materially changes the operational characteristics of the aircraft.

If going to Fuel Injection, don't forget to update your POH and checklists to reflect the new procedures for engine start / shutdown, restart, etc.

Above all, make sure you test to ensure you have full fuel flow to the engine under worst-case conditions... before you run the engine for the first time. It's amazing how easy it is to introduce a little piece of "gunk" into the fuel system when so many components are being swapped.
 
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Thanks for the insight and cautions here. My goal was not to minimize testing. I recognize that I am changing a lot of components here and a good deal of diligence is required to be sure that I got it right and that the components work, including a few different flights with ground checks between them, just as in my initial flights. Clearly I wouldn't carry passengers until I was comfortable that the system was performing well across a variety of scenarios and I had given it some time to settle in and expose it's flaw. I just didn't know if I needed the rigor of the formal Phase I and the FSDO contacts. After all this, I may end up spending 5 hours getting comfortable with the performance and having given this more thought will likely just do the the Phase I testing and document it that way.

Larry
 
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With respect to the wording of the regulation, installation of fuel injection will require the removal of a cockpit control (carb heat) and perhaps installation of new cockpit controls, plus introduction of new procedures for starting, running and re-starting the engine. One could easily and logically argue this modification materially changes the operational characteristics of the aircraft.

This raises an interesting point for me. I plan to fly this plane IFR someday and was considering leaving the carb heat setup after the conversion. My thought was that it could potentially eliminate or reduce water or even ice build up on the air filter when flying in rain. Is there a downside to this approach? I do have an alternate air door to overcome a clogged filter.
 
This raises an interesting point for me. I plan to fly this plane IFR someday and was considering leaving the carb heat setup after the conversion. My thought was that it could potentially eliminate or reduce water or even ice build up on the air filter when flying in rain. Is there a downside to this approach? I do have an alternate air door to overcome a clogged filter.

Leaving the carb heat set-up in tact will NOT cause a problem. As a matter of fact, induction icing is not unheard of with fuel injection. It is rare, but it does happen.
 
I converted my 0-320 to fuel injection. I was required to go back into phase one for 10 hours by local FSDO. When asked why they were very reasonable and produced the data. They had had several major problems with the conversion and were just trying to be safe. No arguments with that
 
Thought I would follow up. I called FSDO this morning. As speculated by others, different FSDO's, different answers. They told me it was an Op's change and only maintenance type documentation is required; No Phase I. The gentleman indicated that it shouldn't change flight characteristics, therefore no Phase I. He followed the guideline from the certified side that states a 10 HP or greater change makes it a Major. Clearly, he recommended flight testing, but stated Phase I re-entry was not required, only logbook documentation.

I still plan to do testing and will do so in un-populated areas and without passengers.

Thanks again for the thoughtful advice here.

Larry
 
Thought I would follow up. I called FSDO this morning. As speculated by others, different FSDO's, different answers. They told me it was an Op's change and only maintenance type documentation is required; No Phase I. The gentleman indicated that it shouldn't change flight characteristics, therefore no Phase I. He followed the guideline from the certified side that states a 10 HP or greater change makes it a Major. Clearly, he recommended flight testing, but stated Phase I re-entry was not required, only logbook documentation.

I still plan to do testing and will do so in un-populated areas and without passengers.

Thanks again for the thoughtful advice here.

Larry

Would recommend asking nicely for an email stating this so you have a record for the future.:) Larry
 
Would recommend asking nicely for an email stating this so you have a record for the future.:) Larry

Or just cover your bases and put it in Phase I long enough to go burn some fuel! Oh the humanity...
 
Another way to look at it

I just didn't know if I needed the rigor of the formal Phase I and the FSDO contacts. After all this, I may end up spending 5 hours getting comfortable with the performance and having given this more thought will likely just do the the Phase I testing and document it that way.
Larry
Edit: As I was composing this and posting, I missed Larry's follow up. I'll leave the following for future reference in case anyone else does a search on the topic in the future...
Hi Larry, it has been my limited experience with putting the plane back into phase one, that it is really very easy, simple, and almost a no brainer. I wanted to install a smoke system, so I called the FSDO and explained what I wished to do. The safety inspector asked me to email a new weight and balance and put it in p1 for 5 hours and make a log book entry when I had tested the installation. You'll have the satisfaction of knowing you did it right and in my humble opinion you will add resale value to your aircraft, as potential buyers will look back and see you did your due diligence and went through the proper procedure. Some seem to think this is a real hassle, but for me it was not. You'll also have a chance to develope a relationship with your FSDO and make contacts that may benefit you in the future.
Just a data point, but it isn't a big deal and I'm glad I did it.
Joe
 
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Phase 1 Test Area

?..Some seem to think this is a real hassle, but for me it was not. You'll also have a chance to develope a relationship with your FSDO and make contacts that may benefit you in the future.
Just a data point, but it isn't a big deal and I'm glad I did it.
Joe

Whether or not this is a "hassle" may depend if one's home field is within a viable Phase 1 test area or not...


Skylor
 
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