Skymaster Forum  

Go Back   Skymaster Forum > Messages
Register FAQ Members List Calendar Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Rate Thread Display Modes
  #1  
Old 06-11-19, 06:13 PM
Ernie Martin's Avatar
Ernie Martin Ernie Martin is offline
Administrator
 
Join Date: Apr 2002
Location: Miami, Florida
Posts: 966
Ernie Martin is an unknown quantity at this point
IMPORTANT ALERT -- Engine quits on takeoff due to undetectable water in fuel

I will give you details in a moment, but here are the findings:

Sumping the fuel tanks and finding no water DOES NOT mean there is no water -- there can be enough to make your engine quit in the middle of your takeoff, and the only way to find out is to lower the tail of the airplane all the way to the ground, raise the tail back up so the airplane is level AND THEN sumping the fuel.

About a month ago, on takeoff, the rear engine quit on my 1977 337G. No stumbling, just quit. I was about 20 - 30 feet above the runway so I shut down the front engine and landed without incident.

On the ramp I did some diagnosis*, including running the engine at full power, and found nothing.

Given the gravity of the incident, and because the Annual was nearly upon us, my mechanic started a painstaking weeks-long effort to find the problem. The injectors were cleaned, the fuel pump checked, all fuel lines checked, and although we felt it was a fuel issue, we also compression-tested the engine and checked all spark pugs and wires. Still nothing.

I then called the big guns: the head tech at Certified Engines, the service rep for Continental Engines in Miami. He checked everything, put the fuel adjustment meters/gauges on the engine, and found nothing.

On a hunch I wondered if there may have been water in the fuel tank that doesn't show when you sump -- and doesn't reach the engine -- when the aircraft is level, but reaches the fuel line to the engine when the aircraft is in its tail-low angle of attack of take off. The suddenness with which the engine stopped, without stumbling, was a strong indicator that this was a fuel issue. And my hunch was also borne of the fact that water had been accumulating in the bowl of the fuel cap on the right wing, from where the rear engine is fed.

To test the hunch, we sumped the right-wing fuel and found no water, just as I had found no water on my ill-fated takeoff. We then lowered the tail of the airplane until the plastic fairings at the bottom of the rudders were nearly touching the ground and after about 15 seconds raised the tail back so the aircraft was level again. When we sumped again we found a significant amount of water. Using a regular fuel tester ASA P/N 13-18464, I must have taken out 4 - 5 tubes full of water, and another 4 - 5 tubes with diminishing amounts of water.

I flew the airplane today, all was well, and I have no doubt that this is what caused my engine to quit. If you have any issues with water not properly draining from around the fuel filler ports, or any doubt about water in your fuel, lower the tail of the aircraft before sumping.

_______________
* I'm a mechanical/aerospace engineer (MS Caltech) and spent 5 years souping-up cars before college.

Last edited by Ernie Martin : 06-11-19 at 06:35 PM.
Reply With Quote
  #2  
Old 06-12-19, 09:44 AM
hharney's Avatar
hharney hharney is offline
Rough Surface
 
Join Date: Jul 2002
Location: Michigan (8D4)
Posts: 1,995
hharney is on a distinguished road
Thank you for posting this as it will trigger me to initiate this technique when suspect to possible water intrusion based on environment and situation.

This is interesting find, and if I remember correctly your airplane is stored outside, correct? I have found that in certain conditions, when parked in the elements, I have had an abnormal amount of water sumped from the tanks. This has only happened once or twice in the 30 some years of managing my plane. I have not tried to angle the plane to see if more water appears but I never typically have any water in my system unless I have been outside, in the hard rain, sitting for a period of time more than 3 or 4 days.

Good to hear you had a non-incident and no one was at risk during this episode.
__________________
Herb R Harney
1968 337C

Flying the same Skymaster for 42 years
Reply With Quote
  #3  
Old 06-12-19, 05:03 PM
Skywalker Skywalker is offline
Registered User
 
Join Date: Dec 2017
Location: POLAND
Posts: 66
Skywalker is on a distinguished road
Water proglems in the fuel

Hello Guys
after hearing Ernie incident , i would highly recommend to install the Monarch fuel caps, ,specially if the plane is parked out side, believe me it will safe you lot of troubles, out of 160 squawks i had during my pre buy , few of them were related due to water in fuel system ,as back engine was not producing enough power among others and it took lot of time and money to resolve those issue and i have installed these caps now.
Dennis
Reply With Quote
  #4  
Old 06-12-19, 07:19 PM
edasmus edasmus is offline
Registered User
 
Join Date: Nov 2006
Location: ARR - Aurora, IL - USA
Posts: 328
edasmus is on a distinguished road
Send a message via AIM to edasmus
Nice job Ernie handling the emergency. I'm grateful all ended harmlessly. Very very fortunate indeed.

I would say water in my fuel is my biggest fear by far. So much so, I have managed to not have my airplane on a ramp in the rain. It sucks for sure. I wish I felt the same about my airplane getting rained on as I do my car but that has never been the case.

I've read this accident report several times on different occasions. One that sticks out in my mind is the C337 departing KPLK, Point Lookout (Branson), MO. The folks had been vacationing there and the airplane had been rained on during the week. Same exact scenario as your situation but if I recall correctly, both quit in that case. The airplane went off the end of the runway and down a steep embankment. It did not end like your case however.

Thanks for posting the information.

Ed
Reply With Quote
  #5  
Old 06-12-19, 10:34 PM
hharney's Avatar
hharney hharney is offline
Rough Surface
 
Join Date: Jul 2002
Location: Michigan (8D4)
Posts: 1,995
hharney is on a distinguished road
Quote:
Originally Posted by Skywalker View Post
Hello Guys
after hearing Ernie incident , i would highly recommend to install the Monarch fuel caps, ,specially if the plane is parked out side, believe me it will safe you lot of troubles, out of 160 squawks i had during my pre buy , few of them were related due to water in fuel system ,as back engine was not producing enough power among others and it took lot of time and money to resolve those issue and i have installed these caps now.
Dennis
Dennis, good call on the updated fuel caps, as our aging aircraft continue to grow old any new and better device is a positive.

Let me discuss one issue that some folks have had that the new caps will not fix. In the service port of our aircraft is an overflow tube that collects small amounts of overflow and allows the fuel to exit under the wing. These small tubes are also suppose to drain any water that may try to collect in this service port when the aircraft is stored in the elements. Everyone should test these drains to be sure they are not broken or cracked. If they are compromised you will not know unless you try this test. Take a small amount of fuel and pour it into the service port, with the fuel cap on, while the bottom of the tube under the wing is plugged. Either have someone pour the fuel while you hold your finger under the tube under the wing or plug the tube with something that will not harm the pipe. If the fuel pools in the service port then the tube is sealed and working correctly. If the fuel drains from the service port then there is a crack or the tube is broken inside the tank. This is how the water intrudes into the fuel cell. I have personally seen this on my airplane and have read from others that this has happened. In fact it was determined that the Skymaster departing Point Lookout in Branson, MO had this very issue. Check your tank drains folks and if you have a problem be very careful when you leave your aircraft in the elements.
__________________
Herb R Harney
1968 337C

Flying the same Skymaster for 42 years
Reply With Quote
  #6  
Old 06-16-19, 12:55 PM
Skymaster337B's Avatar
Skymaster337B Skymaster337B is offline
Registered User
 
Join Date: Jun 2004
Location: New Mexico
Posts: 456
Skymaster337B is an unknown quantity at this point
Please submit an FAA safety report.

https://asrs.arc.nasa.gov/?submit1=Continue
Reply With Quote
Reply


Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is Off
HTML code is Off
Forum Jump


All times are GMT -4. The time now is 12:03 PM.


Powered by vBulletin® Version 3.6.9
Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.