Fly with a bad fuel pump?

[chrixxer]

Mechanic is checking the Mooney books to see if we can do this; I'm leery but the realities of the situation are what they are... New fuel servo installed and piece of rubber removed from the throttle body, mechanic did a run-up and there's still a problem:

 

With the electric fuel pump off, the engine runs fine up to 2200 rpm but then starts gasping. Put the electric fuel pump on and it runs perfectly.

 

He wants to reposition the plane over to KCMA, where he has tools and a proper place to work, we don't have to rely on the availability of an escort to "babysit" the work, etc. Too, the Navy is getting a little impatient having the plane on their ramp for 2 weeks now.

 

It's at KNTD, with a 12,000' runway (and an intersecting 5500' runway). CMA is about 8 miles from NTD, with fields in between.

 

It seems like we could fire it up with the electric boost pump and box climb above NTD to where CMA would be safely within glide range, then head over. If the electric pump goes out on takeoff roll there's more than enough space to abort/get back down. If it goes out above ~1000' AGL, 2200 is enough to maintain altitude and get it over to CMA (or back to NTD I suppose). It's been well gone through at this point and there shouldn't be any more surprises...

 

But I'm totally skeeved at the thought of even trying this...

 

 

 

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[takair]

I would think you would want a ferry permit to do it...if it came to that...but you may not get one.  Even then do you want to risk another engine failure?  I’m sure the FAA and your insutrance company would not be sympathetic.  Don’t forget that the routing of your fuel is from the tank to the electric pump to the engine driven pump and then your servo.  The engine driven pump diaphragm is what really regulates your fuel pressure.  Without knowing what’s going on inside that pump your are at risk.  The electric pump is really intended as an emergency pump....you are currently not in an emergency.  I can appreciate the urge to get it out of there, but the pump is no more difficult to change then the servo.  My 2 cents says stay on the ground and figure out what is wrong.

[Marauder]

Mechanic is checking the Mooney books to see if we can do this; I'm leery but the realities of the situation are what they are... New fuel servo installed and piece of rubber removed from the throttle body, mechanic did a run-up and there's still a problem:
 
With the electric fuel pump off, the engine runs fine up to 2200 rpm but then starts gasping. Put the electric fuel pump on and it runs perfectly.
 
He wants to reposition the plane over to KCMA, where he has tools and a proper place to work, we don't have to rely on the availability of an escort to "babysit" the work, etc. Too, the Navy is getting a little impatient having the plane on their ramp for 2 weeks now.
 
It's at KNTD, with a 12,000' runway (and an intersecting 5500' runway). CMA is about 8 miles from NTD, with fields in between.
 
It seems like we could fire it up with the electric boost pump and box climb above NTD to where CMA would be safely within glide range, then head over. If the electric pump goes out on takeoff roll there's more than enough space to abort/get back down. If it goes out above ~1000' AGL, 2200 is enough to maintain altitude and get it over to CMA (or back to NTD I suppose). It's been well gone through at this point and there shouldn't be any more surprises...
 
But I'm totally skeeved at the thought of even trying this...
 
 
 
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I believe it is listed in the type certificate as a required item.

During my recent flight review my instructor asked me what equipment was required for flight. It’s listed under item 101 below.



You should be able to look up your original type certificate and see if it is listed.


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[Marauder]

And oh yeah, I wouldn’t do it...


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[MikeOH]

This sounds waaay too hinky for me; I'd pass on trying it.

You don't even know what's really the problem so how do you even asses the risk?

[Yetti]

The mechanic has desires to move it.  Unless he has desire to fly it....    I would not do it.   Yes it is more time to do the fuel pump.  Should take about 3 hours to change it out, it can be done with the mags on.  Some people say the mags need to come out, but if you are good at working blind it can be done.   The plane is already in a post maintenance state.   Hopefully they will let you do some fast taxi on their long runway.   The question is between 0 feet and 3000 feet. 

[Yetti]

Oh and you said "should"   Once any of my flying includes a "should" I stop and reevaluate the plan to eliminate the shoulds.

[Boilermonkey]

Get a ferry permit.

[MB65E]

Is there an in-line fuel filter in front of the electric pump that is blocked. Mine has one. 

Also, I would not sign the ferry permit as an IA in the known condition. Was he willing to sign it and do the flight himself? 

“Runs perfectly” is what happens right before it quits.

Take your time, it’ll work out. 

-Matt

[Culver LFA]

My opinion, the question is do you go with a 62B26931 pump or find a LW-15473 before flying the airplane?

I was recently reading on here that the 62B26931 pressures are a bit over Mooney spec.

[HRM]

This is something of an existential dilemma. Frankly, I would delete my account on Mooneyspace ( @bluehighwayflyer) and then go for it. A ferry permit is advised.

Any help from the Navy aviators? Opinions? Suggestions?

[KLRDMD]

1 hour ago, chrixxer said:

It seems like we could fire it up with the electric boost pump and box climb above NTD to where CMA would be safely within glide range, then head over. If the electric pump goes out on takeoff roll there's more than enough space to abort/get back down. If it goes out above ~1000' AGL, 2200 is enough to maintain altitude and get it over to CMA (or back to NTD I suppose). It's been well gone through at this point and there shouldn't be any more surprises...

Go for it. Then when you have your third engine failure you'll know that fate has directed you to buy a twin 

[chrixxer]

Go for it. Then when you have your third engine failure you'll know that fate has directed you to buy a twin 

At that point, I'd start looking into a B-36 or B-52 ("the dreaded 7 engine approach")...


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[Bartman]

You may hav had a bad fuel servo, but knowing this in my WAG is I think the reason you landed on the Navy base was because of a failed fuel pump, not the servo. 

[MyNameIsNobody]

NOPE.

[Guest]

I would not fly the plane until it works correctly, I’m sure that your hosts would understand that the plane still has an issue needing further maintenance.

Clarence

[Hank]

Which option is safer:  repair your plane in the ground at Point Mugu, or trying to fly with a non-functional fuel pump?

"Hope" is a good thing, but should never be part of your flight plan!

Fly safe!

[Bartman]

I would CMA and not fly to KCMA until it is airworthy. 

[Yetti]

1 hour ago, Culver LFA said:

My opinion, the question is do you go with a 62B26931 pump or find a LW-15473 before flying the airplane?

I was recently reading on here that the 62B26931 pressures are a bit over Mooney spec.

I believe those number are for a Non FI Lycoming.  For the FI one I believe this is the pump needed.   Check your Engine parts book to be sure.

41234 TEMPEST O/H FUEL PUMP //Part #: 05-02532

[takair]

1 minute ago, Yetti said:

I believe those number are for a Non FI Lycoming.  For the FI one I believe this is the pump needed.   Check your Engine parts book to be sure.

41234 TEMPEST O/H FUEL PUMP //Part #: 05-02532

Lycoming makes two pumps for the FIs.  I think those are correct...and there is also the non-FI.  Be sure to get the LW pump if you don’t want to go over red line pressure.  The Tempest one also works, as Yetti suggested.  Chris....dig up the thread before ordering to see the history on this or feel free to PM me, it will run fine at the higher pressure...but another thing to get failed on an annual.

[carusoam]

A few ways to look at this challenge....

 

(A)

So I was looking for a positive reason to take the side that says...

• ‘fly it out of there on the back-up pump... that’s why we have a second pump’

But, I haven’t found it yet...   

I have flown a C152 on one magneto... pretty much qualifies as the dumbest flight yet in my flying career.  Too much risk.  Not enough reward... didn’t know what killed the mag... didn’t know if it was going to fall off, or drain the oil...

 

(B)

Check your flight plan for two things...

1) Hope  (did you even think the phrase... ‘I hope this thing keeps working’)

2) Wishful Thinking... (this one comes up later... I wish I finished the maintenance on the ground at Point Mugu...)

If your flight plan has either hope or wishful thinking in it, it is time to modify your flight plan...

 

(C)

Got a contact at the base?

Communicate the steps you are taking to remedy the challenge, and the expected timeline for the steps...

Better to over communicate, then to undercommunicate and take risks...

 

Sports analogy...

I don’t think anyone wants to see you swinging at the next pitch, without first deciding if it’s in the strike zone or not... (not even the Navy)

Not in the zone... don’t swing. You have two strikes already.  No need to go down swinging... call for a time-out.  

 

(D)

Engineer thinking...

When you don’t know what is wrong... There is no way to tell that the back-up system can power its way through the problem for an hour or even a minute... flying on one mag is OK... unless the missing mag is also draining the oil....

 

(E)

Outside of aviation...

In the automotive world... some things cause the fuel pump to die... a clogged filter down stream has a tendency to make the pump work extra hard until it croaks... replacing the pump without changing that filter is a very short term solution....

 

(F)

Risk analysis...

What is the upside to taking some unknown risk...?

Leaving a plane dead stick in a bean field a dozen miles from Point Mugu is going to help who...?  

Pick an elected official on the other side from your preference...   

 

(G)

Insurance challenge...

Who else can make this decision and have your insurance still be in effect?

There is a procedure that probably needs to be followed that probably includes a ferry permit...

Ask your insurance company to make sure they are still covering things... include the worst case... loss of life of your mechanic should he decide to fly it out...

 

(H)

How do maintenance shops handle this kind of thing?

Does your mechanic carry that kind of insurance?

Our MS MSC of record said fix it properly before flying it...

 

Still looking for a reason to say... go fly... but I can’t find one...

Lots of Logic from MS...

Hope that helps...

PP reasoning from everybody else’s thoughts....

Best regards,

-a-

[jetdriven]

even if you wanted to do it, the fact you just revealed the mechanical fuel pump is not right on a public forum, makes it hard to deny if anything goes wrong.  They wont issue a ferry permit for that.

[Jim Peace]

Maybe you could have flown it out the way you described. But you already posted it here for the world to read so you should concider yourself grounded. 

 

[carusoam]

Chrixx,

I probably asked this already...

Got Any JPI data...?

How about some Fuel Flow data?

It really helps to have this stuff when trying to determine the cause of failures...

Could be one cylinder not working right above that rpm...

Could be air entering the fuel through a minor leak...

Would be nice to be able to eliminate fuel pumps from the equation... if they are delivering 18-20gph(?) at full throttle that is typical... if it only gets to 10gph and starts wandering all over the place that is a hint of what is happening with the FF data...

PP thoughts only, not a mechanic...

Best regards,

-a-

[jetdriven]

Maybe your originating issue wasnt the fuel servo, maybe it was mechanical fuel pump failure.  Did you turn on the electric fuel pump as part of your engine failure flow?