Today's Message Index:
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1. 06:45 AM - Re: Elevator Pitch Servo Failure (Bill Watson)
2. 06:52 AM - Re: Re: Elevator Pitch Servo Failure (Bill Watson)
3. 04:16 PM - Re: Elevator Pitch Servo Failure (Eagerlee6)
4. 04:48 PM - Re: Re: Elevator Pitch Servo Failure (Jesse Saint)
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| Subject: | Re: Elevator Pitch Servo Failure |
Thanks for sharing.
I'm at 1100 hours and the trim servo has done more flying than I...
Bill "in the middle of a series of minor 1,000 hour failures" Watson
On 4/14/2019 1:59 PM, Jim Combs wrote:
> Had an elevator pitch servo fail on a flight yesterday. The cable
> pulled out of a hole that uses a set screw to hold the cable in place.
> It's a TruTrak pitch servo. It uses a cable that wraps around a drum.
> Each end of the cable is attached to an aluminum channel.
>
> 1200 hours on the airplane with no prior issues. The pilot said the
> elevator felt funny on any up travel past neutral. He also heard a
> clicking noise as it passed the neutral point.
>
> An engineering EC would be to leave the cable slightly long and crimp
> a sleeve onto the cable as a a failsafe for the set screw(s).
>
> I will call TruTrak tomorrow to see if this should be replaced or
> repaired. I will be adding this to my inspection checklist. I
> noticed nothing during the last condition inspection.
>
> Not sure exactly when it failed. It was noticed prior to a return
> flight from another airport. Removal of the bulkhead and removing the
> control arm of the servo from the elevator bellcrank was done to allow
> the flight home.
>
> N312F - 1200 hours
>
> Jim Combs
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| Subject: | Re: Elevator Pitch Servo Failure |
Seems like an elegant, easy to implement fail safe mod.
I take it that there may not be an easily identifiable failure mode
where the elevator does jam, but the fact that a stiff control arm could
be flopping about is enough to justify a fail safe mod.
Thanks for sharing!
On 4/14/2019 7:12 PM, bill.peyton wrote:
>
> Hi Jim,
> I was always concerned with this design of the pitch servo. I spoke with TT
about it 8 years ago and they assured me they had redesigned the force multiplier
to remedy this issue. Yours is not the first time this has happened. Just
consider yourself extremely fortunate that the arm did not jam the entire elevator
operation.
> I designed a fail-safe retainer to prevent this from happening should the cable
come loose. I also shared this with TT. Here are a few photos of my modification.
>
> --------
> Bill
> WA0SYV
> Aviation Partners, LLC
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=488739#488739
>
>
> Attachments:
>
> http://forums.matronics.com//files/img_1940_270.jpg
> http://forums.matronics.com//files/img_1939_314.jpg
> http://forums.matronics.com//files/img_1937_412.jpg
> http://forums.matronics.com//files/img_1936_183.jpg
> http://forums.matronics.com//files/img_1935_180.jpg
> http://forums.matronics.com//files/img_1933_207.jpg
> http://forums.matronics.com//files/img_1934_160.jpg
>
>
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| Subject: | Re: Elevator Pitch Servo Failure |
I have a two axis TruTrak DigiTrak autopilot with an AlTrak altitude hold and did
NOT install the torque multiplier. When the elevator trim is set for light
stick pressure the pitch servo has no problem(in 140 hours) keeping the altitude
correct. Does anyone else use the stock servo without the enhancer?
PH
On Apr 15, 2019, at 12:44 AM, RV10-List Digest Server <rv10-list@matronics.com>
wrote:
______________________________Message 2 _____________________________________
Time: 11:33:03 AM PST US
From: Jim Combs <jiminlexky@gmail.com>
Subject: RV10-List: Elevator Pitch Servo Failure
Had an elevator pitch servo fail on a flight yesterday. The cable
pulled out of a hole that uses a set screw to hold the cable in place.
It's a TruTrak pitch servo. It uses a cable that wraps around a drum.
Each end of the cable is attached to an aluminum channel.
1200 hours on the airplane with no prior issues. The pilot said the
elevator felt funny on any up travel past neutral. He also heard a
clicking noise as it passed the neutral point.
An engineering EC would be to leave the cable slightly long and crimp
a sleeve onto the cable as a a failsafe for the set screw(s).
I will call TruTrak tomorrow to see if this should be replaced or
repaired. I will be adding this to my inspection checklist. I
noticed nothing during the last condition inspection.
Not sure exactly when it failed. It was noticed prior to a return
flight from another airport. Removal of the bulkhead and removing the
control arm of the servo from the elevator bellcrank was done to allow
the flight home.
N312F - 1200 hours
Jim Combs
Message 4
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| Subject: | Re: Elevator Pitch Servo Failure |
We had the standard Servo in the beginning. It worked ok, but the torque enhancer
was much better.
Jesse Saint
Saint Aviation, Inc.
jesse@saintaviation.com
C: 352-427-0285
F: 815-377-3694
Sent from my iPhone
> On Apr 15, 2019, at 7:15 PM, Eagerlee6 <eagerlee6@gmail.com> wrote:
>
>
> I have a two axis TruTrak DigiTrak autopilot with an AlTrak altitude hold and
did NOT install the torque multiplier. When the elevator trim is set for light
stick pressure the pitch servo has no problem(in 140 hours) keeping the altitude
correct. Does anyone else use the stock servo without the enhancer?
>
> PH
>
>
> On Apr 15, 2019, at 12:44 AM, RV10-List Digest Server <rv10-list@matronics.com>
wrote:
> ______________________________Message 2 _____________________________________
>
>
> Time: 11:33:03 AM PST US
> From: Jim Combs <jiminlexky@gmail.com>
> Subject: RV10-List: Elevator Pitch Servo Failure
>
> Had an elevator pitch servo fail on a flight yesterday. The cable
> pulled out of a hole that uses a set screw to hold the cable in place.
> It's a TruTrak pitch servo. It uses a cable that wraps around a drum.
> Each end of the cable is attached to an aluminum channel.
>
> 1200 hours on the airplane with no prior issues. The pilot said the
> elevator felt funny on any up travel past neutral. He also heard a
> clicking noise as it passed the neutral point.
>
> An engineering EC would be to leave the cable slightly long and crimp
> a sleeve onto the cable as a a failsafe for the set screw(s).
>
> I will call TruTrak tomorrow to see if this should be replaced or
> repaired. I will be adding this to my inspection checklist. I
> noticed nothing during the last condition inspection.
>
> Not sure exactly when it failed. It was noticed prior to a return
> flight from another airport. Removal of the bulkhead and removing the
> control arm of the servo from the elevator bellcrank was done to allow
> the flight home.
>
> N312F - 1200 hours
>
> Jim Combs
>
>
>
>
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