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ACRO E-mail Archive Thread: Yak-52 engine failure on T.O.

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ACRO E-mail Archive Thread: Yak-52 engine failure on T.O.


Thread: Yak-52 engine failure on T.O.

Message: Yak-52 engine failure on T.O.

Follow-Up To: ACRO Email list (for List Members only)

From: N77TW at

Date: Tue, 05 Nov 1996 22:57:57 UTC


  A recently re-assembled Yak-52 was scheduled for it's first flight.  The
engine had been run for approximately 40 minutes prior to takeoff.  Nothing
unusual was noted.  A thorough preflight was accomplished, including several
runups to 70% and the mags and prop were checked per the manufacturer's
manual.  Nothing unusual was noted.  The engine was run briefly at full power
and a mag check was accomplished.  

When cleared onto the active and in position with fine pitch selected, the
throttle was  fully advanced.  All engine instruments check normal, including
fuel pressure, oil temperature and pressure.  The aircraft accellerated
briskly to 90 kph at which time the aircraft was rotated (book value).  At
110 kph the ship broke ground and continued to climb with the engine running
at 100% and sounding strong.  With a positive rate of climb, the gear was
raised and the climb continued.

At about 100 feet, the engine lost power and briefly made sputtering sounds.
 The nose was lowered to maintain stall margin.  The engine  coughed and very
briefly  seemed to develope some power, then sputtered again.  The pilot
 immediately dropped the nose, pulled the throttle back, selected gear down.
 The aircraft was held  off the ground as long as possible, allowing the gear
to re-extend.  The aircraft touched down in the grass/dirt over-run.  Full
brakes were applied and the aircraft maneuvered to avoid adjacent homes and
vehicles, impacting a small wooded shed and coming to rest against a
chainlink fense.

There were no injuries, no fire and aircraft damage was limited to wings
(probably both will have to be replaced).

This happened last Friday.  This Monday,  under FAA supervision, the prop was
replaced and the engine was started.  After several false starts, the engine
was capable of running at no more than 30% if, and only if, the primer
plunger was vigorously worked in the Cylinder position.

Current thinking is that there is a problem with the pressure carb.  If you
have knowledge or experience with this type of problem, I'd like very much to
have your input.

If you are assembling or flying anything with an M14P engine, be aware, as
there were no tell-tail signs of this empending problem.

A Russian mech arrives on this Thurs, so, I may have more information then.

Also, I'd like to post this to the YAK Pilot is someone knows the URL.

Bill Bancroft
n77tw at


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