Vapor Lock

For you guys flying injected engines.

I'm flying a Cessna P206C with the Continental IO-520. It quite often
will quit on rollout after landing. I'm being told that it is probably
vapor lock causing an interruption in fuel flow. I'm not convinced.
The ambient temps are in the 60s to 70s. The airplane is being used to
haul skydivers so it's a climb from 250 MSL to 13000MSL, then a power
descent back down for the landing with the engine well leaned. Cowl
flaps are opened on base or final once the speed is down to 100IAS or so
(this is being done to help prevent the vapor lock). Today the airplane
cutout right after liftoff, it was as if the throttle had been pulled
back, I noticed the fuel flow was fluctating at about 1/2 or less the
normal flow rate for takeoff. Only lasted a moment and power returned
before I could get the boost pump on. It then ran normally up to 13K.
An inspection has not found anything in the fuel system (filters,
screens, injectors, etc). Again, I was told it was probably vapor lock.
I'm not convinced. G

Has anyone experienced anything similar? Does your injected engine quit
on rollout? Have you experienced vapor lock during high power
operation? or at anytime other than start?

I also fly a turbo-charged P206 that doesn't suffer from the "vapor
lock" problem.

--
Dale L. Falk

There is nothing - absolutely nothing - half so much worth doing
as simply messing around with airplanes.

http://home.gci.net/~sncdfalk/flying.html

On Fri, 06 Aug 2004 22:21:13 -0800, Dale wrote:

For you guys flying injected engines.

I'm flying a Cessna P206C with the Continental IO-520. It quite often
will quit on rollout after landing. I'm being told that it is probably
vapor lock causing an interruption in fuel flow. I'm not convinced.
The ambient temps are in the 60s to 70s. The airplane is being used to
haul skydivers so it's a climb from 250 MSL to 13000MSL, then a power
descent back down for the landing with the engine well leaned. Cowl
flaps are opened on base or final once the speed is down to 100IAS or so
(this is being done to help prevent the vapor lock). Today the airplane
cutout right after liftoff, it was as if the throttle had been pulled
back, I noticed the fuel flow was fluctating at about 1/2 or less the
normal flow rate for takeoff. Only lasted a moment and power returned
before I could get the boost pump on. It then ran normally up to 13K.
An inspection has not found anything in the fuel system (filters,
screens, injectors, etc). Again, I was told it was probably vapor lock.
I'm not convinced. G

Has anyone experienced anything similar? Does your injected engine quit
on rollout? Have you experienced vapor lock during high power
operation? or at anytime other than start?

I also fly a turbo-charged P206 that doesn't suffer from the "vapor
lock" problem.

Dale,

My fuel injected engine is a Lycoming IO360 and the only time it quit on
rollout was after I had landed at Leadville, CO (9928' MSL). I attributed
that to the mixture being too rich for that altitude.

Other times when it "almost quit" on rollout were when the idle setting
required adjustment.

So perhaps checking your idle and mixture adjustments would be a place to
start.


--ron

I had my carb'd O-360 quit shortly after takeoff and traced it to a mud-dauber
nest in the fuel line on the right tank. It was fine in cruise when the fuel flow was
lower, but on full-rich takeoff the pump couldn't pull it through the partial blockage
fast enough. I'm not sure how the 206 is plummed, but partial blockages could cause
the takeoff problem.

Vapor locking does sound like a potential culprit. You don't burn much fuel
for the entire descent so any fuel in the engine compartment hangs out for awhile and
cooks.... especially with cowl flaps closed to keep from shocking the cylinders. I
wouldn't be surprised if you've got two problems, though.

-Cory

Dale wrote:
: For you guys flying injected engines.

: I'm flying a Cessna P206C with the Continental IO-520. It quite often
: will quit on rollout after landing. I'm being told that it is probably
: vapor lock causing an interruption in fuel flow. I'm not convinced.
: The ambient temps are in the 60s to 70s. The airplane is being used to
: haul skydivers so it's a climb from 250 MSL to 13000MSL, then a power
: descent back down for the landing with the engine well leaned. Cowl
: flaps are opened on base or final once the speed is down to 100IAS or so
: (this is being done to help prevent the vapor lock). Today the airplane
: cutout right after liftoff, it was as if the throttle had been pulled
: back, I noticed the fuel flow was fluctating at about 1/2 or less the
: normal flow rate for takeoff. Only lasted a moment and power returned
: before I could get the boost pump on. It then ran normally up to 13K.
: An inspection has not found anything in the fuel system (filters,
: screens, injectors, etc). Again, I was told it was probably vapor lock.
: I'm not convinced. G

: Has anyone experienced anything similar? Does your injected engine quit
: on rollout? Have you experienced vapor lock during high power
: operation? or at anytime other than start?

: I also fly a turbo-charged P206 that doesn't suffer from the "vapor
: lock" problem.

: --
: Dale L. Falk

: There is nothing - absolutely nothing - half so much worth doing
: as simply messing around with airplanes.

: http://home.gci.net/~sncdfalk/flying.html

--

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering Ph.D. Graduate Student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

In article ,
"John Clonts" wrote:

Must've been pretty disconcerting on climb-out though-- how high were you at
the time?

About 20 feet. The bad part is from our strip the no-go point is before
liftoff. Made for a tense departure. G

--
Dale L. Falk

There is nothing - absolutely nothing - half so much worth doing
as simply messing around with airplanes.

http://home.gci.net/~sncdfalk/flying.html