Engine-out due to no fuel pressure
in General Tech Discussion
7 years ago
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Re: Engine-out due to no fuel pressure
by Roger Lee » 7 years ago
One other thing to consider is angle of bank and or decent. Depending on where the fuel pick up is inside the tank and with a decreased fuel level you can un-port the fuel away from the pick up tube and it will make the engine think it ran out of fuel. I have seen this several times.
Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-349-7056 Cell
Thank you said by: Gottfried Thoma
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Re: Engine-out due to no fuel pressure
by Bill Hertzel » 7 years ago
Summarizing...
Thailand, High Temperatures, High Altitudes.
Failure occurs after a long climb/cruise and/or after a throttle reduction.
A Hot Engine compartment and a reduced fuel flow at Idle/Descent are present.
The condition resolves itself after the engine has cooled for a while in the glide.
Sounds like a classic Vapor lock situation.
Are you using Auto-Gas or Avgas 100LL?
Confirm that the fuel lines are insulated in Fire Sleeving and are not routed near/above the Exhaust/Muffler/Cylinder heat sources.
An auxiliary electric fuel pump located close to the fuel tanks or at least right at the point where the fuel lines enter the hot zone is recommended.
This pump will add pressure to the fuel lines and prevent the vapor bubble from forming or collapse the bubble if it has already formed.
Bill Hertzel
Rotax 912is
North Ridgeville, OH, USA
Clicking the "Thank You" is Always Appreciated by Everyone.
Thank you said by: Gottfried Thoma
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Re: Engine-out due to no fuel pressure
by Gottfried Thoma » 7 years ago
Garrett, thanks for the info. I've read the article about the new fuel pump and it's good to know how it works. Also, quite reassuring to read that most previous problems seem to be resolved.
My fuel pump, which malfunctioned, is still the old one from 2010 (soon to be replaced with the new one).
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Re: Engine-out due to no fuel pressure
by Gottfried Thoma » 7 years ago
Roger, thanks for your comment which I will keep in mind.
When I had engine-out at 7,500 feet, I was flying straight-and-level at 5,000 RPM for about 20 minutes with fuel reserves of about 2 hours (about 40 liters/10 gallons). The AP was on.
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Re: Engine-out due to no fuel pressure
by Gottfried Thoma » 7 years ago
Bill, thanks for your comments. Appreciate it.
I checked an instrument picture which I took shortly before I had the engine-out at 7,500 feet. On my Dynon EFIS, OAT was 17 degrees C (~62 F) and the stated density altitude was 9,600 feet. EGT's, CHT's and fuel pressure were all in the green.
I'm using Auto-Gas 95. I confirm that the fuel lines are insulated in fire-sleeves and are not routed near/above the exhaust/muffler/cylinder heat sources.
As of now, vapor lock appears to be the most logical conclusion but I'm still baffled how this can happen at straight-and-level flight for 20 minutes at 7,500 feet PA (9,600 feet DA). I understand that the service ceiling for the Rotax 912 ULS is 15,000 feet.
As you've pointed-out, high non-standard temperatures might be a key issue leading to vapor lock. At 7,500 feet, the standard temperature should be 0 degrees C (32 degrees F) but my OAT was 17 degrees C (~62 F).
Glad that I now have a workable auxiliary electric fuel pump as back-up.
Since I will continue flying in Thailand with high non-standard temperatures, are there any other ways to prevent or minimize vapor lock?Engineoutat7500feet15.8.2018.jpg (You do not have access to download this file.)
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