One would have naturally thought
that a "3rd Generation" PSRU would
be the "cat's meow"; but that evidently isn't the case, and
it almost
cost a pilot and pax in an RV-9A their lives!  The
below report (see
link) also states that there have been quite a few failures
of this
PSRU, and one came after only 160 hrs of usage! Amazing the
"snake oil"
that is out there and ready to hurt people...

http://www.ntsb.gov/aviationquery/brief2.aspx?ev_id=20140224X15602&ntsbno=ERA14LA130&akey=1

     Marc Wiese

     AIRPLANE INFORMATION

     According to Federal Aviation
Administration (FAA) records, the
RV-9A, a two-seat, all-metal, low-wing airplane with
tricycle configured
landing gear was issued an airworthiness certificate, in the

experimental category, on July 18, 2011. It was built from a
series of
kits provided by Vans Aircraft and Eggenfellner Aircraft,
Inc. The
airplane was equipped with an Eggenfellner Subaru H4
modified automobile
engine which included a Gen 3 V4 propeller speed reduction
unit (PSRU)
gearbox that was used to drive the propeller at a speed
slower than the
engine speed. The engine was equipped with an IVO propeller
assembly
that consisted of three electrically-controlled wooden
propeller blades.

     The engine kit was based on an
EJ-25, 2.5L Subaru water cooled
4-cylinder engine and was rated at 160 HP at 5400 rpm.

     The pilot/builder stated that he
purchased the kit for the airplane
in 2001 and began construction shortly after. He purchased
the engine,
which at the time, was equipped with a Gen 1 PSRU and solid
flywheel,
direct from Eggenfellner Aircraft, Inc. in 2002 and
installed the engine
about January 2008. In 2011, prior to receiving the
airworthiness
certificate, the pilot employed Eggenfellner Aircraft, Inc.
to remove
the original PSRU and replace it with a Gen 3 V4 PSRU.

     During a telephone interview a
representative of Eggenfellner
Aircraft, Inc., now defunct, stated that the Eggenfellner
Subaru H4
engine transfers power to the PSRU through a spline shaft.
One end of
the spline shaft is inserted into a splined drive disk
adapter at the
engine. The splined drive disk is bolted to the engine
crankshaft
through the flywheel. The other end is inserted into the
PSRU input spline.

     The spline shaft and PSRU input
spline were taken from the transfer
cases of Nissan Pathfinders. The machining of the drive disk
adapter
that affixes to the solid flywheel and crankshaft were
outsourced to a
separate facility and made from non-heat treated 4140
steel.

     The engine information system (EIS)
installed in the cockpit showed
that the total time for the airframe and engine at the time
of the
accident was 324.5 hours

     The last recorded annual inspection
took place on September 13,
2013, at which time 278 hours were reported. A review of the
maintenance
records revealed no record that the PSRU had been removed or
that the
spline components had been inspected or lubricated since
installation.
In addition, the pilot/builder of the airplane stated that
he had not
inspected or lubricated the PSRU, the spline shaft, or drive
disk
adapter during the airplane's total time in service.

     Removal of the PSRU revealed that
the spline shaft rotated freely
within the drive disk adapter, which was attached to the
engine solid
flywheel. The PSRU input spline contained approximately one
teaspoon of
red dust (consistent with ferrous fretting-wear debris). The
drive disk
adapter and spline shaft were then removed from the flywheel
and
separated. The teeth of the spline shaft exhibited
mechanical damage
consistent with the wear on the drive disk adapter teeth.

     Further examination at the NTSB
Material's Laboratory revealed that
the PSRU input spline, spline shaft, and drive disk adapter
exhibited
severe wear and were void of lubrication. Examination of the
spline
shaft and drive disk adapter using a 5X to 50X stereo zoom
microscope
revealed the flanks of the spline shaft teeth that mate with
the drive
disk adapter were worn by about 75%, with the tips of the
teeth forming
sharp cusps that had been bent over consistent with rotation
of the
spline shaft within the drive disk adapter. Wear surface
features on the
spline shaft teeth were consistent with fretting wear that
had
progressed to adhesive wear. [Additional information can be
found in the
Materials Laboratory Factual report located in the public
docket.]



I thought everyone long since knew to not use an
Eggenfailure PSRU.
Strange that he would have used one without even doing any
inspections
given their propensity to fail. (even the 3rd generations)

Does anyone know if this is the usual failure mode for these
drives.
Tracys PSRU also includes a spline mated with the
flywheel.  I never
noticed any wear before, but its been a couple hundred hours
since last
inspection.  It does seem that Tracy's input
shaft/spline is hardened.
I assume that could make all the difference in the world.

Dave Leonard

Tracy box's. The torque on that end is limited to 200 foot
pounds and the
spline is right out of the C6 A4OD tranny. I think he cuts
the drum off.

Paul Lamar



Hi I have been following your emails for a number of years, wanting to switch out my lycoming 320 for rotary, I found a rotary package to buy for a Mustang 2 and was wondering if the PSRU failure are common.  The fire wall forward engine was built by tracy crook from real world solutions, now retired, I know he does great work but was looking for advise on any problems that have come to light such as the hardness mismatch problem.

He listed the PSRU as follows
RWS RD1C 2.85 to 1 PSRU

Any advise is appreciated.  Thanks, Jake Link

No that's the good one. Nothing wrong with that. 10 pounds heavier than a Ross
but it will last 100's of hours. Make sure the oil supply to the gear box is not
shared by the turbo charger if any.

Please send pictures of the engine.

Paul Lamar

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