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jma201

Engine trouble on takeoff-I was lucky.

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I've had a few days to calm down and thought I would share an experience hoping it might be of use to someone else.  I've gained a lot from this forum over the years without posting or commenting much.  I hope to change that going forward.  Especially when I have something that might be useful to others.  I apologize for just lurking for so long.

After a two hour cross country on Monday with no issues, I landed at my local airport to refuel before heading home to our private strip.  On takeoff just after gear up the engine loss 90% power.  I was able to recover and land on the runway after a scramble to get the gear down.  I think it lock in about 30 ft. above the ground.     I rolled to the end of the runway with the engine barely making power.  I was able to keep it running by pulling the mixture back to about an inch before cutoff and taxied to my local A&P's shop on the field.  Luckily he was there and came out just before I shut the engine down.  His first thought was that I had a valve stuck because it was backfiring back through the exhaust.  

Here is what we found.  It appears the Bendix Fuel Servo failed and flooded the engine with excessive fuel.  All four spark plugs we equally fouled.  The engine just could not handle the extra fuel and basically flooded.  There is no other apparent damage to the engine.  We are still investigating to be certain, but after calls to Lycoming we are pretty sure that is what happened.  Any other insights are surely welcomed. 

Lessons learned.  First:  Always use every inch of available runway!  Second:  Do not put off maintenance on the fuel system.  As I understand it, the TBO for the Bendix Fuel system is equal to that of the engine.  We had a factory overhaul at 1500 hours or so and have only put 800 or so hours on the engine since that time.  However, there is also a time TBO of twelve years regardless of engine hours.  That is what I ignored.  We are past that time limit by several years.  Big mistake that could have cost me the airplane or worse.

I was very lucky that I was on a 5,000 ft runway and not the 2800 ft private strip at home.  That would have been a disaster.

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Glad to have your Pirep, JMA

Somebody recently detailed a similar fuel system failure with it going too rich....

Now trying to find that thread may take some search skills.

See if @chrixxer knows this one? Might be somebody else...

Best regards,

-a-

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Yes, I had the same although my EDM alerted me to high fuel flows before the engine quit. Actually I tried to lean the engine below 20 gph and then it quit so I pushed it back and landed with black smoke. 

Then I made a mistake. I sent the servo to a fuel shop who said they knew what the problem was and would just repair it vs overhaul. Reinstalled, looked good, on climb out got an alarm again for high fuel flows. 

I believe this is the 3rd time my EDM has prevented me from an off field, engine out landing.

-Robert

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Is this the cause of these events? I know one was saying lean running condition in the bulletin.

sim20-115.pdf?t=1535754703082

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14 minutes ago, INA201 said:

Is this the cause of these events? I know one was saying lean running condition in the bulletin.

sim20-115.pdf?t=1535754703082

This SB does not apply to my circumstance.  From what I understand from my A&P, there are two diaphragms inside the servo.  One our both failed causing the excessive fuel.

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1 hour ago, INA201 said:

Is this the cause of these events? I know one was saying lean running condition in the bulletin.

sim20-115.pdf?t=1535754703082

I believe the diaphragms just get old and brittle. 

-Robert

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5 hours ago, carusoam said:

Glad to have your Pirep, JMA

Somebody recently detailed a similar fuel system failure with it going too rich....

Now trying to find that thread may take some search skills.

See if @chrixxer knows this one? Might be somebody else...

Best regards,

-a-

Not mine, at least, not exactly. On mine, the fuel servo probably wasn't bad - I'll have to dig through the logs but IIRC the fuel servo was well within calendar and time TBO - but I replaced it anyway, abundance of caution.

In my loss of power event, the fuel servo had ingested part of the ram air intake door gasket, which was stuck in the throttle body. .  I think that somehow caused a cascade(?) failure of the mechanical fuel pump, somehow, because even after the fuel servo was replaced, the mechanical pump wasn't supplying proper pressure (<4 psi) and wouldn't make power above ~2000 rpm. So I put on a rebuilt mechanical fuel pump, too. That still wasn't quite right (fuel PSI on the gauge was too high, like 34 psi IIRC), but flyable, per the local A&P working on it (a MooneySpacer referral). Flew it to CMA (~6 miles away) where the A&P tore it apart to fix "everything." (Mags IRAN'd, p-leads, plug wires, reinstall (properly) the baffles, etc, oh, and, as long as he's in there, full annual, pitot-static check, etc.)

If I had to guess, maybe pulling the mixture back dislodged part of the gasket? Or maybe the gasket was blocking enough air flow that the regular mixture settings were too rich. Or ... IDK.

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There is no way that FOD caught in the fuel servo can cause a mechanical fuel pump to fail.

 

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5 hours ago, RobertGary1 said:

I believe the diaphragms just get old and brittle. 

-Robert

I should take a pic of mine after it failed spectacularly (well, it seemed that way) and I flew my Mooney sailplane to the nearest runway.   They do glide damned well with the gear and flaps up.  I wound up having to slip it on final to get down all the way.

The overhauler said the servo was "full of grit" and gave me back all the old parts including the gaskets and diaphragms.   Casual inspection of one of the diaphragms leads one to the obvious conclusion that somewhere along the way it spent a fair amount of time about half-filled with water.   Whatever had happened to it, when it decided it was done with life it went suddenly, just like with jma201.    There was no warning and it failed to a sputtery, backfiring idle.    When we got on the ground we had to taxi up a slight incline and it barely made it at full throttle.   No mixture or ignition setting had any influence on it.    It did clear up after quite a long ground run, but I wasn't about to fly it anywhere and the shop at the field did an awesome job of handling the issue. 

There is no redundancy in the fuel servo, and as many people as have documented issues with them after long service lives it's probably a good idea to respect the TBO on them.   My engine had probably 1450 hour or so on it when it went TU, and I don't have any records of it getting any specific attention prior to the overhaul, if then.

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@jma201 great job on getting it back on the ground safely!

Do you by chance have any downloadable engine data to go with that? If not, @RobertGary1 makes an excellent case on how it could be helpful providing some warning; even on the takeoff roll. Anyway would love to see the data if you have it. But thankful you are here to tell us about it!

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58 minutes ago, kortopates said:

@jma201 great job on getting it back on the ground safely!

Do you by chance have any downloadable engine data to go with that? If not, @RobertGary1 makes an excellent case on how it could be helpful providing some warning; even on the takeoff roll. Anyway would love to see the data if you have it. But thankful you are here to tell us about it!

Unfortunately I do not have any data.  EDM is now definitely on the list of things to do.

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20 hours ago, jma201 said:

I've had a few days to calm down and thought I would share an experience hoping it might be of use to someone else.  I've gained a lot from this forum over the years without posting or commenting much.  I hope to change that going forward.  Especially when I have something that might be useful to others.  I apologize for just lurking for so long.

After a two hour cross country on Monday with no issues, I landed at my local airport to refuel before heading home to our private strip.  On takeoff just after gear up the engine loss 90% power.  I was able to recover and land on the runway after a scramble to get the gear down.  I think it lock in about 30 ft. above the ground.     I rolled to the end of the runway with the engine barely making power.  I was able to keep it running by pulling the mixture back to about an inch before cutoff and taxied to my local A&P's shop on the field.  Luckily he was there and came out just before I shut the engine down.  His first thought was that I had a valve stuck because it was backfiring back through the exhaust.  

Here is what we found.  It appears the Bendix Fuel Servo failed and flooded the engine with excessive fuel.  All four spark plugs we equally fouled.  The engine just could not handle the extra fuel and basically flooded.  There is no other apparent damage to the engine.  We are still investigating to be certain, but after calls to Lycoming we are pretty sure that is what happened.  Any other insights are surely welcomed. 

Lessons learned.  First:  Always use every inch of available runway!  Second:  Do not put off maintenance on the fuel system.  As I understand it, the TBO for the Bendix Fuel system is equal to that of the engine.  We had a factory overhaul at 1500 hours or so and have only put 800 or so hours on the engine since that time.  However, there is also a time TBO of twelve years regardless of engine hours.  That is what I ignored.  We are past that time limit by several years.  Big mistake that could have cost me the airplane or worse.

I was very lucky that I was on a 5,000 ft runway and not the 2800 ft private strip at home.  That would have been a disaster.

I had a similar incident in my 231 but I was fortunate enough that mine cut out just prior to rotation speed.  My issue was fuel in the upper deck likely due to leaking seals and also a trashed impeller.  Don Maxwell recommended a great shop in Justin TX to overhaul it and that shop gave me an earful about not overhauling it every 10 years, mine had 13 years since reman.  They were  right, and with people flying less these days, more airplanes aren't to TBO after 10 years or so, and are waiting to TBO for the fuel system overhaul.  Big mistake as you and I learned the easy hard way.  20 seconds later and it would have been a disaster for me.  

Please be proactive with your fuel system maintenance.  

 

 

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11 hours ago, kortopates said:

@jma201 great job on getting it back on the ground safely!

Do you by chance have any downloadable engine data to go with that? If not, @RobertGary1 makes an excellent case on how it could be helpful providing some warning; even on the takeoff roll. Anyway would love to see the data if you have it. But thankful you are here to tell us about it!

My EDM-830 showed no tell-tale signs of abnormality before the event, I'm not sure if jma201 would have seen anything, but I do agree that it's possible that it could have detected impending failure.  

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Next annual I will 2200+ hours and 22 year old engine...what parts should I consider overhauling: servo, pump? Can someone point me where Lycoming publishes separate TBOs for engine parts?

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Based on this thread, I just got off the phone with JD and we'll be taking a look to see when my servo was last overhauled. I'm also going to have them look at the flow divider on my TSIO360 as well. I'm pissing a bit of fuel out the vent hose on landing and it's a bit concerning as well.

Thanks for all the good info in this thread. MooneySpace is valuable in spite of all the bull shit ;)

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My fuel servo was replaced at this last annual in April.  It had a small leak, which is very creepy in its own right because that means it was leaking fuel onto a hot engine!

jma201 I am so very glad all is well with you!!!

Edited by aviatoreb
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Continental engines don’t have Bendix fuel injection servos like Lycoming engine do, unless you have a Piper Seneca with TSIO-360RB engines.

Continental engines don’t regulate fuel flow based on an airflow diaphragms, they do it based on engine RPM, pump RPM, pump unmetered and metered fuel pressure and mixture plate position.

Clarence

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OK I've seen enough of these IO-360 fuel servo threads and I'm spooked.  I'll have it done this December at annual time.  Been gathering up supplies and I'll be down for some time while I'm rebuilding the top half of the cowl too :):)

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I used Aircraft Carb and Injection Service of Texas.  I'm pretty sure these guys rebuild everything and they did a great job on my continental TSIO-360 fuel system.  

http://aircraftcarbs.com/index.html

 

 

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Mine had not been overhauled since 1989. The system seemed to operate fine but it looked terrible and the linkage was getting sloppy.  I sent the components off to Russ at D&G Supply and he did a great job. The servo and divider now look brand new.

http://www.dgsupply.com/about-us

 

 

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Took a pic of the diaphragm that came out of mine:

 

20180907_185933.jpg

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