Mailing List lml@lancaironline.net Message #28951
From: Dennis Johnson <pinetownd@volcano.net>
Sender: Marvin Kaye <marv@lancaironline.net>
Subject: Legacy Speedbrakes
Date: Wed, 16 Mar 2005 19:36:42 -0500
To: <lml@lancaironline.net>
Greetings,

I'm building a Legacy and want to thank everyone who has posted to this list
for all the help you have given me.  Here's something I found out that might
help others.

As strange as it sounds, Precise Flight says they don't provide instruction
manuals or any kind of documentation to experimental builders installing
their speedbrakes.  I explained to them that with five electrical
connectors, each with eight pins, that makes 32,768 different combinations
and they sent me a wiring diagram.

I subsequently had a nice conversation with Precise Flight tech support, who
was very helpful answering my questions,  I found out some things that might
be of interest to other Legacy builders installing Precise Flight
speedbrakes.

1.  The speedbrakes should be installed so that the milled face of the
blades face forward.  The perfectly flat side of the blades face aft.
Another way to determine this is that the narrow side of the top channel
faces forward.  He said that some of the older speedbrakes came with
electrical cables that were too short to conveniently allow this.  He didn't
think it was the end of the world if they were installed "backwards," but
thought it would be worth making longer cables and doing it the recommended
way.

2.  If the case is electrically grounded to the black wire coming out of the
speedbrake, it does not need to also be separately grounded.  Older
speedbrakes were not wired this way and should be grounded with a separate
wire connected to the case.  You can test for continuity between the case
and the black wire; continuity means no need for an extra ground wire.

3.  Once a year, add a small amount of grease (not oil) to the brass ring
gear visible through a small hole in the speedbrake assembly.

4.  Every month or so, while on the ground, extend the speedbrakes and, with
them still extended, pull the circuit breaker.  Both speedbrakes should
immediately slam closed.  If one doesn't slam closed, it means the clutch is
bad and needs to be replaced.  After the ground test, restore the circuit
breaker and cycle the speedbrakes to complete the test.

5.  Make sure the drain tube in the wings for the speedbrake dry bay is kept
open.  If the dry bay fills with water, it will ruin the speedbrake.

Dennis Johnson
Legacy #257
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