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Shinn / Firestone Aircraft Brakes Overview
The Shinn (Firestone) brake system is a simple and moderately effective light
aircraft brake circa 1940. Notes for its care and feeding are below.
A great preliminary overview of Shinn Brakes and their operation by Rob Lees
is located at:
http://www.taylorcraft.org.uk/Brake-issues.pdf
Caution is necessary for the owner and pilot operating a certified airplane
with these brakes because deviations from approved procedure can cause failures
or affect the airworthiness of the product on certified or insured aircraft to
the detriment of the owner.
A clarification of some of the website comments for those operating certified
airplanes is necessary as follows:
- The use of any of the antique brake systems for other than parking or
low speed ground handling is not recommended. Even bad brakes can overpower
flight controls and lead to disastrous consequences. Also, older brake
systems are often poorly maintained and poorly adjusted, leading to
unpredictable application results.
- Some of the comments by Mr. Lee are modifications to type design that
are not approved by FAA/CAA etc. Use of those methods without obtaining
approval can void insurance and aircraft airworthiness conditions on a
technicality- but you loose.
- Heat shrink is a great idea. None of the "clamping off" methods
demonstrated by Mr. Lee in his article are FAA accepted. The use of nico-press
collars and swaged fittings are generally recognized as acceptable for use
on certified airplanes.
- Increasing cables from 3/32" to 1/8" is a type design change. More
importantly the change in cable size also increases the minimum radius
required for the pulleys considerably. See FAA AC 43.13 and cable
manufacturer specifications. (Recommended minimum radius for 1/8" cable is
about 1.5", requiring a 3" pulley)
- Riveting of the shoe to the drum is with Copper or more typically Brass
rivets.
- Weld build-up on the actuating wedge may or may not be an approved
repair to the part. This is an area requiring great caution due to how the
weld heat may affect the metal and function of the part. Replacement is
advised or anneal and heat treat after welding.
- Linings have generally been available from Donna Losey at www.luscombesilvaire.info 480-650-0883,
on request.
- Use of adhesives. While this author personally agrees with Mr. Lee on
the benefits and reliability of adhesives, their application is a design
change and not approved by regulatory authorities in this application.
Doug Combs is an Airframe and Powerplant mechanic with FAA inspection
authorization delegation. He has worked with antique and certified aircraft for
more than 30 years.
Copyright © 2004, Douglas Combs
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