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Nearly Gave up General Aviation Flying After this Incident


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1 hour ago, M20Doc said:

 None get out of bed thinking I’m going to screw up at work and kill someone as a result of my actions today.

I have gotton up thinking I hadn't tighten the oil drain plug on a customers motorcycle after servicing. Called the customer and told them not to ride it and went to their house to check and make sure. 

1 hour ago, M20Doc said:

Many trades and careers have far higher pay scales, the lack of available talent is a now is a result of this.  How many posters race to the bottom for pricing then complain about the outcome? 

40 yrs ago I looked at going to Spartan's in Oklahoma and becoming an A&P but starting pay after 2 yrs of school was less than what I was currently making working part time as a Motorcycle mechanic. When I retired my labor rate was $15.00 an hour higher than my IA's, but the local Avionics shops were 20 buck an hour higher than me, go figure

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After landing my ‘78 J years ago, I noticed gas dripping on the nose wheel tire. The B nut on the output line of the fuel pump was loose. Never smelled gas. Tightened it, checked all the others and Torque Sealed them all. Never had another problem. Plane was ten years old at the time. No indication in the logs that line had been touched since manufacture. Stuff happens. 

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One thing I Have learned at MS...

Fuel smells occur in old planes... (sounds reassuring, as if this is normal)

Fuel smells occur in new planes too...

New or old... There are no Fuel smells that are normal...

If the plane isn’t moving and you smell fuel, it may be a small leak... fuel sender seals are known to leak... and flow into the cabin under the rug at your kids’ feet...

If you smell fuel while the plane is screaming through the air at 180kias... that fuel leak is being diluted by tens of thousands(?) of CFM of air... and your nose is still picking it up... that is probably not a small leak... if it is,  it is getting heated...

Every now and then a fuel injector has fuel exiting through its air vent...  proper placement of the vent usually solves the fuel escape...

The area on the fire wall where Allegro’s fuel line is, may also have the FF sensor plumbed in there. The silicone fire sleeve usually wraps around everything carrying fuel including the FF sensor...

One thing to consider... for knowing if you have a fuel leak... it requires really accurate FF data from two different sources...

1) the ship’s FF sensor on the firewall is pretty close to the end of the fuel system and does a good job of totalizing all the fuel used...

2) Cies fuel level sensors are reported to be able to show fuel used as well... accurately enough to compare one system to the next...

3) Some math to consider... If you smell fuel, your cies system says you have used 50.0 gallons and your FT101 says you used 50.0 gallons, and your flight plan said only 40 gallons were supposed to be used... 10gallons left the system after the FF/totalizer...a strong hint that says my nose and totalizer are telling me to land soon/next opportunity....

4) more math... the cies system says 50.0, and your FT101 only says 40.0... a hint that there is a leak... but it is happening before the engines totalizer....

5) It would be really nice to know where the leak occurred on Allegro’s plane... i’ll Try to review the pics a little closer...

6) Holy Cow, Allegro! You did a great job, plus you came back and gave a full report!

7) The Comfort of flying a plane comes from knowing as much as you can about them...  even then, it’s been a really tough week.  Learn to recognize something that’s not right...  Fuel aromas are one of those things... exhaust leaks are another...

Thanks for sharing the details.

Best regards,

-a-

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@Mooney_Allegro

I spun a few of the pics to help people reviewing what you posted...

I added some notes from things I remember people discussing above... have a look...

 

When you are reading about turbo system parts... V band clamps note... you know the blue stains are in the area of some really hot parts...

ED782578-BD0A-4BDF-938C-009346ED7E6A.jpeg

3A2BBAF8-71E2-4353-8571-AB8641622E7F.jpeg

 

The following picture is the one that interests me the most... the silicone fire sleeve looks like a snake that ate a mouse... and appears to have a few wires running out the right side... somebody noted above the nylon ty-wraps probably aren’t correct...

Check the Log books to see what/when the shop installed the JPI or other engine monitor... the rat inside the snake is most likely the FF sensor... two fittings, one going in, the other going out....  the sensor is typically a cube shaped block, not really a rat... :) the outbound fitting is on the left...

Take a look to see if those wires are actually exiting from under the silicone, squeeze to feel if it’s a cube... or take the silicone off to torque the fitting parts... compression fittings and other tube fittings really take some experience to seat properly... same thing with O2 lines...

0200C4AC-F671-4A7B-9BF2-7400D7D422E0.jpeg

6F0F2C6C-DE26-4000-A12E-DCC96259EFCB.jpeg

 

The value of knowing which fitting was leaking... we can learn something about detection of the failure... often air gets drawn into some leaks and start giving bad FF readings...

Got any JPI data that you can upload to Savvy?  Or is this a G1000 with no engine data saved?

PP thoughts, regarding the pics in this post... I am not a mechanic... just some stuff I think I remember reading about around here... trying to be helpful... supporting the importantance of this conversation...

Best regards,

-a-

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@curusoam,

First off, thanks for your comments.  I have a bit more information to add to the mix.  The plane has a G1000 with a datacard to record aircraft engine parameters.  I'm a Savvy subscriber for over a year now, so they have the downloaded info, and I was able to find it.   My fuel flow for most of the affected flight was under 18 gph.  At about 45 minutes prior to landing, the FF spiked up to 35 gph for 5 minutes, then returned to normal.  This must have been when the G1000 "range-ring" showed I had about 5 minutes of fuel.  

I checked my engine logbook after the leak was fixed last October, and the corrective action was, "Tightened fuel line on fuel transducer, leak check good".   It was a five minute fix.  

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8 hours ago, carusoam said:

The value of knowing which fitting was leaking... we can learn something about detection of the failure... often air gets drawn into some leaks and start giving bad FF readings...

This seems like a downstream leak so fuel pressure transducer.   It's on intake where leaks cause bad performance.   Sucking air....

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Sadly no matter how well trained or how well intentioned the technician is things still can and do go wrong.  None get out of bed thinking I’m going to screw up at work and kill someone as a result of my actions today.
From the TN manual here are the torques.
Clarence
BD1FF612-FE62-40AD-9D30-FDAE9D38211A.thumb.jpeg.c7f9ef111a9ca6c414f679639756d546.jpeg
This is an important thing to remember for sure. Emotions can get high when you start to think about, "what might have happened."
Nobody goes to work with the intention to kill somebody, well, I guess there are a few.
In the pilot world, we talk a lot about distractions. In the airline world, it is a huge subject. We have systems set up in place to combat distraction.
Distraction doesn't get talked about a lot in the maintenance side of things. Shops have a ton of distractions And it is very easy to forget something even as criticals a fuel line.
I had a friend years ago with the same situation in a stearman. She had a fuel leak and didn't know it, the plane ran out of gas long before it was supposed to and she crashed in the Ozarks. Messed her up pretty good.

To the OP: you bring up another interesting point; confirmation bias. This is insanely powerful! how easy it is to convince yourself that the problem is one thing and discount another.
That is quite the fuel leak, I'm glad you were diligent! Sometimes it just takes being observant after a flight. I always postflight. During this time, I have caught several things... The least of which was a gear door that was hanging by one screw.



Sent from my Pixel 2 XL using Tapatalk

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Definitely sucks to think about what could have happened.  I clearly remember flying over the Sierras with my dad when I was ~10 and him tapping the fuel gauges a lot.  Finally he decided to land halfway between Mammoth and Camarillo, only a 2 hour flight?!  When we stepped out of the fuel injected sky hawk, fuel was still dripping out of the cowl.  Quickly found several injectors that weren’t even finger tight.  2nd flight after annual.  How did that airplane get us over the mountains?!  How did it not burn?

Fast forward to my M20F.  Within the first few weeks, blue streaks on the cowl.  Opened it up to find a loose injector and fuel goo all down the exhaust pipes.  Scary.

 You can’t catch every leak. No way.  But your nose is a good indicator.  Knowing your systems is also good.  I have very accurate JPI gauges with relatively accurate senders that I double check at each fillup.  Separately, the JPI uses fuel flow to compute fuel used and fuel remaining - which is only accurate if set correctly at the start. If the gauges and the computed fuels don’t match, find out why.  If the gauges/computed remaining doesn’t match your plan, find out why.

On the G1000, the range ring is nice, but put FOD (Fuel over destination) up on the mfd.  It is computed from the starting fuel you set and from FF.  It’s a really quick way to compare your plan to what’s actually happening.  Compare that to your tank gauges as a final sanity check.

Did the airplane really have 20 gallons remaining as the gauges indicated?

Edited by Ragsf15e
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So this is not a Mooney... unless we finally got that PT6 STC, but 3 different airplanes I’ve flown with G1000 all had FOD.  

I don’t think it would have done you anymore good than the range ring but it’s my technique as the range ring is a bit too fluid for me.

FDF256C5-43D9-4F71-B80F-6DCD1B3201C7.jpeg

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35 minutes ago, Raptor05121 said:

What is FOD? Fuel On Descent?

Fuel Over Destination.

It isn’t perfect, as it’s computed at your current fuel flow and ground speed (so sometimes negative in the climb) but it’s a good check at level off and in cruise.  More meaningful to me than the range ring for my fuel checking.

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1 hour ago, Ragsf15e said:

Fuel Over Destination.

It isn’t perfect, as it’s computed at your current fuel flow and ground speed (so sometimes negative in the climb) but it’s a good check at level off and in cruise.  More meaningful to me than the range ring for my fuel checking.

Also available on Flightplan page. Mine ties out almost perfectly with ForeFlight and actual fuel when I refuel.

 

TBM930 I flew had a nice weight/runway calculator built in, too.  

-dan

Edited by exM20K
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1 hour ago, Ragsf15e said:

Fuel Over Destination.

It isn’t perfect, as it’s computed at your current fuel flow and ground speed (so sometimes negative in the climb) but it’s a good check at level off and in cruise.  More meaningful to me than the range ring for my fuel checking.

Garmin previously used Fuel Left on Board (FLOB) on the 530 and 430.  I think FLOB is more fun to say, and doesn't get confused with other acronyms :) 

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This is one reason I replaced all of the factory engine instruments in my M20F. Phil at Avon Park discovered my fuel pressure line was weeping onto my exhaust. The line runs from somewhere on the fuel system to the firewall. The fuel pressure gauge in the panel has a braided hose that runs from the firewall to the instrument. Fuel goes into the back of your panel. That line had never been changed. 

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5 minutes ago, Hyett6420 said:

FOD is and always has been to me Foreign Object Damage, and I dare say it means the same to anyone with a military aviation background, be that Naval or otherwise.  Its not safe when we reuse well known acronyms for something else.

As retired USAF I agree with the foreign object damage acronym... but it’s tough to have 23 gallons of Foreign Object Damage! ;)

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This is one that always hits home.  Like it or not what we do is dangerous.  We can be as careful and prescient as possible, and our number can still come up for something for which we are entirely blameless.  Aircraft are machines, they can and do break, and sometimes those malfunctions leave us in a very bad spot.

The one thing for which I am truly grateful is still today the number one cause of airplane accidents is the PIC.  Don't fly low, and stay the heck away from bad weather and you're more likely to avoid Mr. Murphy.  Doesn't mean he can't rear his nasty head, but it is somewhat less likely.

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30 minutes ago, steingar said:

This is one that always hits home.  Like it or not what we do is dangerous.  We can be as careful and prescient as possible, and our number can still come up for something for which we are entirely blameless.  Aircraft are machines, they can and do break, and sometimes those malfunctions leave us in a very bad spot.

The one thing for which I am truly grateful is still today the number one cause of airplane accidents is the PIC.  Don't fly low, and stay the heck away from bad weather and you're more likely to avoid Mr. Murphy.  Doesn't mean he can't rear his nasty head, but it is somewhat less likely.

Definitely agree!  Add a couple more easy/inexpensive things... recurrent training, flying often, checklist discipline, and thinking through (chairfly) critical phases of flight.  We could all use work on some of these.  Won’t stop every accident, but every little bit helps!

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4 hours ago, Hyett6420 said:

FOD is and always has been to me Foreign Object Damage, and I dare say it means the same to anyone with a military aviation background, be that Naval or otherwise.  Its not safe when we reuse well known acronyms for something else.

Same thing in aerospace manufacturing environments; Foreign Object Damage.

FLOB is much better for the fuel acronym:D

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The auto ignition temperature for most gasoline is less than 600 degrees F.  Most likely the only thing that prevented ignition was having too lean of a mixture around the hot surfaces inside the cowl.  So keeping your speed up and cowl flaps open no doubt helped keep it lean. Probably the biggest risk of ignition was during the taxi on the ground before and after flying. 

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