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Very important

So today i went out to plane and started it . Everything seemed perfect until  I did my run up... all seemed good. But then the engine just  quit. I put the boost pump on and the engine restarted. The it quit again....!

If the engine did not stop i would never have known that i had a problem

I stopped the plane to find out that fuel was pouring out the cowl flap. I would not have seen that or even known about that if i was in sitting in the plane.

Now under another thread last week i asked about a flickering low fuel pressure gauge .

Maybe that  was the start of the problem or the first indication.

And i suppose we all have different experiences but this  is one i do not wish to repeat. But i actually dont know how you could know you had this problem

I got out of the plane to find the gas flowing out of the cowling.

I got the  plane was operating I have no idea whether this plane would have had the power to take off  with a failed engine driven fuel pump or  if i would have  hit the high boost while "on the roll"/ would it have had the power to take off 

I just dont know if i missed an indication of  pending doom or not.

last week i reported a very tiny ficker in the  fuel gauge needle and discussed it here . Most thought it was normal.

I had no fuel stain on the ground  when i pulled the plane from the hangar and i did not have any hint of this issue.

The mechanic pulled the cowling and confirmed that fuel was flowing from the engine driven fuel pump and the feeling is that when the fuel pump fails that it will just spit out gas and even more gas if  you turn on the high boost pump

Thank goodness i caught this on the ground. I had no indication and the only way i would know if i had a problem was if i saw fuel leaking ( not possible I'm in the plane ) or a zero fuel indication. 

Very scary 

Thoughts.   Peter

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Yea, I had a mechanical fuel pump failure a couple months ago but mine occurred upon startup...the engine wouldn't idle without the low boost pump. Your engine is larger than mine but I would strongly suspect you would have detected a serious problem when you started your takeoff roll....probably sputtering or lower power with low fuel pressure reading. Our engines/planes typically tell us when there is a problem...even in flight. You are fortunately that you did not have to deal with fire.

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You have defined a possible failure that could happen while flying...

Depending on where your FF sensor is, it should be showing the extra gushing out overboard...

Early in the T/O run, I try to check FF as confirmation of power being delivered...

It is also a memory check in the event I forgot to push the red knob all the way in.

An IO550 turning 2700rpm will be drinking 27.2 gph at sea level. 

 

If you want to know if you have a fuel system leak you are going to need a fuel totalizer and the new digital CIES fuel floats...  both systems, compared to each other, will indicate a problem...

-if they read differently, there is a leak before the FF sensor.

- if they read the same, but higher than expected, one is confirming the accuracy, the other is indicating the fuel is going somewhere at a high rate.

 

Another thing to check on... was the fuel exiting a drain designed into the pump's casing?  That is the drain for when one of the diaphragms splits, or a seal leaks... (?)

Was the fuel draining anywhere near the exhaust pipe? This adds a whole new level of emergency...

PP ideas only, not a mechanic...

Best regards,

-a-

Edited by carusoam

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Im not completely sure i understand how to determine a leak on the ground or if fuel is leaking. ( BTW all temps and fuel flows appeared  normal) . I have a totalizer but flows  looked normal to me and even if it did not it would not show something excessive like  30 gallons on the ground

I think you are right in that the plane tells us we have an issue

I did two run-ups. The first look all good. Mag checked at -125 each 25 diff

I went to slow idle then it quit. If the engine had not quit i would have gone and tried to fly

I restarted then did another run-up... this time mags were -250 about 30 diff

then i went to slow idle an i had a hesitation ,( that was the clue ) this plane so far never hesitate , it is solid and then a  backfire. 

I scared the hell out of myself.. "why would my plane quit" . it was perfect last flight

I taxied back to the hangar and took a deep breath

Any way i shut it down and fuel was flowing from the cowl flaps.

Once shut down the plane , the fuel stopped running , but when i turned on the high boost ( plane off ) gas was flowing from the cowl flaps

Everyone tells me this was a busted engine driven fuel pump but regardless I find it difficult and scary.  I had this happen to me 500 hours ago on a J. I lost an oil seal. 

Almost wants to make me stop flying!!!

Peter

 

 

 

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Peter,

If it makes you feel better...

Nobody is chiming in to say... 'yeah, that happened to me too...' last week, last month, or last year...

By working closely with your mechanic...  ask him to show you what failed.  The more you know, the better your problem identifying and solving skills become.

The part I like the most...  you identified something amiss, documented it in detail, shared it with the Mooney community, and didn't take it flying to see what would happen next...

Put a copy of that in the perfect flight category.  :)

My only failed fuel pump experience comes from my electric pump. It split a diaphragm and would pee like a race horse with the pump on.  The pump is never on while I'm outside the plane.  Can't see the leak from the inside. A bystander waved at me to let me know something wasn't right...

The sign I didn't notice was the variation in priming prior to start.

Some things are going to be a challenge to identify from inside the plane.  But there are so many additional tests and pre-flight things people do, we learn a ton, just by listening...

Side note, both fuel pumps we have are dual diaphragm.  There is going to be a leak, but the safety back-up should keep it running.  If it is leaking on the exhaust pipe, this can be disastrous... check where the pump drains are.  An extension tube can be added if necessary...

how is that for PP knowledge? Not a mechanic...

Best regards,

-a-

 

 

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As always excellent advice..You right i could not see anything whilst in the plane.

There are allot of mooney bravos so i cant be the only one who has had this problem

All i can do is listen , learn and get back on the horse when I'm ready and I feel things are safe

I will ask for some pics and a description of the issue so that i can share it here

Thank you

Pete

 

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5 hours ago, carusoam said:

Peter,

If it makes you feel better...

Nobody is chiming in to say... 'yeah, that happened to me too...' last week, last month, or last year...

By working closely with your mechanic...  ask him to show you what failed.  The more you know, the better your problem identifying and solving skills become.

The part I like the most...  you identified something amiss, documented it in detail, shared it with the Mooney community, and didn't take it flying to see what would happen next...

Put a copy of that in the perfect flight category.  :)

My only failed fuel pump experience comes from my electric pump. It split a diaphragm and would pee like a race horse with the pump on.  The pump is never on while I'm outside the plane.  Can't see the leak from the inside. A bystander waved at me to let me know something wasn't right...

The sign I didn't notice was the variation in priming prior to start.

Some things are going to be a challenge to identify from inside the plane.  But there are so many additional tests and pre-flight things people do, we learn a ton, just by listening...

Side note, both fuel pumps we have are dual diaphragm.  There is going to be a leak, but the safety back-up should keep it running.  If it is leaking on the exhaust pipe, this can be disastrous... check where the pump drains are.  An extension tube can be added if necessary...

how is that for PP knowledge? Not a mechanic...

Best regards,

-a-

 

 

Where was the excess fuel draining from on your electric pump failure?

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I found this reference to Bravo fuel pump failures in an older aopa article from several years ago

"Fuel is carried in two integrally sealed sections of the forward, inboard area of the wing. Total usable fuel capacity is 89 U.S. gallons. The recessed three position fuel selector, allows the pilot to set the selector valve to LEFT tank, RIGHT tank or OFF position. The electric boost pump is capable of supplying sufficient pressure and fuel flow to the engine for rated engine performance should the engine driven fuel pump fail."

This still does not make sense to me

I have been told that in the event the engine driven fuel pump fails and if i then turn on the boost pump , the fuel will potentially not be pumped into the engine.

In my case this appears to be somewhat true as after failure ( engine off and boost pump on ) and gas just( "pee'd ) out the cowl flap

Contradiction:

it also goes on the say that , in the event of an engine driven pump failure, turning on the boost pump will supply enough fuel to keep the machine flying. Is that true?

This is a contradiction ( either the fuel goes into the engine or it gets pumped overboard ?

Im confused.... can anyone clarify so i understand how this actually works and emergency procedures because the POH is not completely aligned with these comments

Thank you Peter

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I had a mechanical fuel pump fail but I noticed it before complete failure. I happened to notice deviations of the fuel pressure at the time. As mentioned above there is a dual diaphragm and when the first gave way I could only notice it in fuel pressure variations. I didn't really notice much performance difference in the plane but when I had the mechanic looked at the fuel pump he knew right away it needed to be replaced.

One of several nice things about having an engine monitor with primary instrument replacement are the alarms, warnings and the ability to track engine parameters at home with the downloadable data. I bet you would seen and known about the up coming fuel pump failure by looking at your data downloads. 

These are always good times to review the power loss checklist as this thread has stimulated me to do once again!

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In my plane you have a low and a high boost pump, I'm not sure about the Bravo. Low is for partial mechanical pump failure high is for complete mechanical pump failure. If your mechanical pump fails but is still producing a little fuel and you hit high boost you will flood the engine. The idea is to give the engine what it needs. First start with low boost and if that's not enough go with high. I'm sure with high boost on you will loose fuel overboard through the failed mechanical pump. In general in my plane with excess fuel pressure the excess fuel is returned to the tanks.

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Just now, kmyfm20s said:

In my plane you have a low and a high boost pump, I'm not sure about the Bravo. Low is for partial mechanical pump failure high is for complete mechanical pump failure. If your mechanical pump fails but is still producing a little fuel and you hit high boost you will flood the engine. The idea is to give the engine what it needs. First start with low boost and if that's not enough go with high. I'm sure with high boost on you will loose fuel overboard through the failed mechanical pump. In general in my plane with excess fuel pressure the excess fuel is returned to the tanks.

Is that a J ? . My bravo only has  a high boost pump...which interestingly will comes on automatically when full power is applied

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I just looked at the M vs R POH. In the R we have a return line from the mechanical pump for the excess full to return to the tanks. In the M that does not exist. You have 1 boost pump setting and we have 2 hi/low. Since you don't have the return line I would bet if you have excess fuel pressure the fuel goes overboard.

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2 minutes ago, kmyfm20s said:

I just looked at the M vs R POH. In the R we have a return line from the mechanical pump for the excess full to return to the tanks. In the M that does not exist. You have 1 boost pump setting and we have 2 hi/low. Since you don't have the return line I would bet if you have excess fuel pressure the fuel goes overboard.

You are correct..... one pump and it goes overboard... Im super careful and methodical with my pre flight and process ( but i dont have eyes under the plane so i had no way of knowing if things are dripping), in getting ready to fly. It just proves you cannot ever be " over confident"  and  one must always be hyper-aware of the nuances of the  machine. Learn it and recognize all and any changes from "normal" as they may point to a problem , then question and learn!

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A couple things come up here...

1) Lycoming and Continental supply the fuel pumps and plumbing for each system.

2) Expect some similarities. But know there are airframe specific differences.

3) not all fuel pump failures are the same... losing the drive system off the pump is easier to describe than having a seal leak.

4) When the mechanical pump drive fails, the electric pump can power the fuel through the failed mechanical pump. Yay!

5) When seals let go...  it is less clear how the failure is overcome.  But it is a good possibility Fuel is going to leak out of the system...

6) when the seals let go in my O, fuel departed through the integral drain nipple of the pump.  Pump OH, is a simple R&R using the pump shop of choice... pay the man, get it fixed... takes a few days...

7) A POH review will show the details of the plumbing system.

8) Match all the drains and vents to the physical devices coming out the bottom of the plane...

9) fuel, air, spark. You need all three. There are Plan Bs for all three.

10) there is no single failure points left in these well developed systems.  But you have to make sure the systems are working as expected to avoid flying with a failure already occurring...just waiting on the second point to occur.

PP thoughts only.  Older planes are a bit more challenging than newer planes.  None are trouble free...

Best regards,

-a-

 

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1 minute ago, carusoam said:

A couple things come up here...

1) Lycoming and Continental supply the fuel pumps and plumbing for each system.

2) Expect some similarities. But know there are airframe specific differences.

3) not all fuel pump failures are the same... losing the drive system off the pump is easier to describe than having a seal leak.

4) When the mechanical pump drive fails, the electric pump can power the fuel through the failed mechanical pump. Yay!

5) When seals let go...  it is less clear how the failure is overcome.  But it is a good possibility Fuel is going to leak out of the system...

6) when the seals let go in my O, fuel departed through the integral drain nipple of the pump.  Pump OH, is a simple R&R using the pump shop of choice... pay the man, get it fixed... takes a few days...

7) A POH review will show the details of the plumbing system.

8) Match all the drains and vents to the physical devices coming out the bottom of the plane...

9) fuel, air, spark. You need all three. There are Plan Bs for all three.

10) there is no single failure points left in these well developed systems.  But you have to make sure the systems are working as expected to avoid flying with a failure already occurring...just waiting on the second point to occur.

PP thoughts only.  Older planes are a bit more challenging than newer planes.  None are trouble free...

Best regards,

-a-

 

Is #4 actually true for a bravo... It would relieve some stress but I have had conflicting opinions as to whether the boost pum could get the plane off the ground or once in the air back to the ground. I always thought that was why we had a electric boost pump in the first place. So my understanding is that the boost pum is there to provide for this exact potential eventuality

Btw and interestingly I have an edm700 and it was indicating all normal

What was not normal was after the engine quit my mag's were indicating a drop of 250 each..

More intrigue !!!

 

Peter

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Being only a PP, I am not familiar with the pump sizes for the Bravo, or their design flow rates...

The POH probably has some descriptions for what happens when the mechanical pump fails.

There is no way to test the electric pump because there is no way to turn off the mechanical one...

If the Bravo is set up the same as the O, Both pumps are used during full throttle operations... if one fails, there isn't going to be a complete back-up for the failed pump.

The pilot is going to still be needed. No robots yet...

Best regards,

-a-

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1 hour ago, pkofman said:

Is #4 actually true for a bravo... It would relieve some stress but I have had conflicting opinions as to whether the boost pum could get the plane off the ground or once in the air back to the ground. I always thought that was why we had a electric boost pump in the first place. So my understanding is that the boost pum is there to provide for this exact potential eventuality

Btw and interestingly I have an edm700 and it was indicating all normal

What was not normal was after the engine quit my mag's were indicating a drop of 250 each..

More intrigue !!!

 

Peter

#4 has to be true, from a design perspective...

The pumps are in line with each other.  They are sized similarly.

 

Unfortunately there are ways to fail the fuel system in the most pedestrian of ways... they don't pump air very well... they don't know the difference between fuel and water, or 100LL and jet fuel...

Fear is an excellent motivator.  Use it to drive the desire to read some boring POH pages.  :)

 

The O's fuel system is sooo cool.  Two fuel pumps. Two settings for the electric pump. Excess fuel gets returned to the same tank it is supplied from (complex fuel selector valve to match).  And, the boost pump comes on automatically with full throttle.

With all the good comes some challenge.  If the fuel flow gets blocked to the engine, the FF indicator shows the flow, but the pilot can't tell it is going back to the tank...  testing this theory is as simple as pulling the mixture knob all the way back to idle cut-off, turn on the electric pump, watch the FF indicator.  The FF indicator shows a reading of the fuel going back to the tank or the ground depending on the system...

The single point failure is most often the pilot, followed by the controls he has.  A simple broken prop control or throttle control can be pretty serious.  Keep reading and training...

other situations add to the challenge.  High DA and full loading of the plane uses the full capabilities of the system design. If the system isn't performing 100% the pilot needs to know his options.

Best regards,

-a-

Edited by carusoam

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1 hour ago, carusoam said:

 

If the Bravo is set up the same as the O, Both pumps are used during full throttle operations... if one fails, there isn't going to be a complete back-up for the failed pump.

 

I can't find any reference for the fuel pump automatically turning on for the R or S models only the M. I thought I might not have this since my plane is an S with the Sreaming Eagle conversion but looking at POH's and un cowled planes of both model I haven't been able to see how that happens. I know when its hot out I turn it on for take offs to keep the fuel from vaporizing.

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It is an IO550 detail...

Now, Where to find that detail...? Hmmm....

I would expect to find the description in the POH regarding the fuel system.  I'll have to check that when I get some time.

The O has some interesting systems like the air fan / blower comes on automatically when the windscreen / Defog is used...

Old fuzzy memories, may be inexact... please check my details.

Best regards,

-a-

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What kind of variation in priming would you see prior to start if the electric fuel pump were going bad, like you mentioned earlier? @carusoam

Edited by Davarron

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What i was asking above is if the M model boost pump would  soley run the airplane so it would continue to fly after a main pump failure . There is nothing automatic here, I fully expect i have to hit the boost pump if the engine driven pump fails. and/or  the engine quits or stumbles. 

The answer what i can discern  is the boost pump should run the plane in the event of failure of the main pump 

But , if and as in my case the seal or diaphram ruptures in the main pump  , then when I put  the  boost pump on,  the fuel is going to go overboard and not into the engine . Hence why i had fuel everywhere . 

I have always been taught that proper procedure was boost pump on when landing and follow the POH on takeoff. ( On the mooney you check to see if the blue light boost pump in on when doing the final take off roll checks) .

 

Peter

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The answer is yes but your POH say you need to reduce the manifold pressure. It doesn't look like it can maintain enough pressure for full power.

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We have an 1999 Eagle and recently while trying to get the low fuel flow set noticed fuel leaking out of the pump underneath the plane. I'm told these fuel pumps ( on the IO 550) tend to leak out of the seals when they go bad. It was rebuilt and is fine now. I don't know if it was intentional by Continental but the pump mounts low on the back of the engine right in the middle. So when it leaked it would drop down into the belly, between the exhausts and out. Seems like the best you can hope for and least chance of ignition. Still a very scary sight, glad we were on the ground when spotted!

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On 6/8/2017 at 6:52 PM, carusoam said:

You have defined a possible failure that could happen while flying...

Depending on where your FF sensor is, it should be showing the extra gushing out overboard...

Early in the T/O run, I try to check FF as confirmation of power being delivered...

 

 

I believe all fuel flow transducers are AFTER your fuel pumps, just before your fuel distribution mechanism (carb'ed or injected).  A fuel leak before the transducer will not be evident in the FF instrument.

Tom

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