Marsh Brothers Aviation First Ever Grease-Free Landing Gear Is Proving To Be A Success

July 25, 2018

Marsh Brothers Aviation First Ever Grease-Free Landing Gear Is Proving To Be A Success

It was a long time ago that Jimmy Mullen fell in love with Aerostars. It’s a love affair that, according to the founder of Marsh Brothers Aviation, Sandy Thomson, has lasted even longer that Jimmy’s love affair with his wife Laurie.

Sandy told me that years ago when Jimmy started coming to Aerostar meetings he was “just a kid”!

Well, I guess that’s how it starts with most Aerostar owners.

I’m not an aircraft owner or pilot. I’m an aerospace engineer, with a deep passion for anything that flies and/or goes fast! I have had the good fortune to have worked for fifteen years for two of the world’s largest landing gear manufacturers; Goodrich and Safran. When I learned of the plans Sandy and his parent company had for upgrading the bearing and seal positions in GA aircraft, I could see the opportunity for an exciting adventure for myself and for Marsh Brothers Aviation, leading a revolutionary change in the aircraft industry.

Marsh Brothers got its start making aircraft bushings and seals many years ago when the Canadian Warplane Heritage Museum was rebuilding their iconic Lancaster bomber. They came to Thomson-Gordon Group, the parent company of Marsh Brothers and asked for help in rebuilding the landing gear of this aircraft.  We designed and produced customized landing gear seals, which have been in service now for more than 20 years! 

At the time, Marsh Brothers decided to move seriously into the design and manufacture of upgraded components for commercial landing gear; Sandy was flying his Sea Fury as a business airplane. He had owned an Aerostar 601P in the late 1980s and felt it was the perfect size to test the capabilities of the new polymer AeroTough GF.  AeroTough GF is a proprietary polymer developed by the Thomson-Gordon Group, a manufacturer of bearings, seals and engineered mechanical components for diverse global markets since 1911.

In 2012, Sandy purchased his second Aerostar and decided to give this aircraft a complete makeover. Throughout a three year period, every bushing and seal in the landing gear was re-designed and made from Thor-Flex for the seals and wipers, and AeroTough GF for the bushings. Since then, Marsh Brothers has obtained STC’s from Transport Canada and FAA for landing gear bushings, shock strut lower and upper bearings, and the MLG floating piston; along with all static, dynamic and environmental seals. To date, Sandy’s corporate Aerostar has logged more than 400 hours with the AeroTough GF equipped landing gear.

The relationship with Jimmy Mullen was an obvious one. Jimmy was the ideal source for providing Marsh Brothers with a supply of landing gear cores from a decommissioned aircraft.

Jimmy wanted a higher level of engagement, and as a result a partnership evolved. Jimmy’s company has developed their own capabilities, to the point where landing gear upgrades can be done out of his La Belle Florida facility using all Marsh Brothers supplied kits.

Earlier this year a complete set of landing gear units were overhauled and upgraded for Jimmy’s aircraft.  An aircraft painter from a previous life, Jimmy chose to repaint and refit his 601P with a gear set previously supplied to Marsh Brothers from another Aerostar.

In June of 2017, Jimmy completed his paint work and stripped the gear from his airplane. The conversion required the removal of all bronze alloy OEM bushings, replacing them with AeroTough GF. This includes the airframe trunnion bushings.

Ingenuity being a hallmark of every airplane owner, Jimmy demonstrated the use of two puller arrangements; one fabricated from large sockets, washers, and threaded rod and another puller supplied by Snap-on.

The brake anchor block bushings can see a lot of heat. High levels of heat can cause a tire to ignite which may also result in bushing damage. In addition, the steel bushings used that allow the brake callipers to self-adjust can seize against the pins, resulting in uneven pad wear. There is no lubricant that can last in an environment of brake dust and runway/taxiway dirt over such a large temperature range.

At the aircraft interface, airframe trunnion bushings were fitted to receive the main gear and drag brace pins. The jury brace pins for the nose gear is where relative movement occurs during gear retraction and extension. Jimmy had used threaded rods and washers to press these bushings into position. Once fitted the zerk fittings were removed and were replaced with tapered stainless steel socket headset screws fitted into the holes and lubrication is now no longer needed!

It is the perfect time at this stage to inspect the nose gear area for cracks referenced in Jim Christy’s article in the last Log. If a repair is needed, now is the time to do it.

After flying his airplane for several weeks, Jimmy has decided to put his grease gun up for sale on eBay.

With roughly 400 hours on Sandy’s aircraft since the makeover, and no signs of abnormal wear, it is safe to say that the Aerostar gear upgrade project has been a success.

Jimmy installed the greaseless landing gear upgrade in his personal Aerostar 601P N601DJ. The install was completed July of 2017, and since then he has flown his airplane over a 100 hours. Jimmy stated, “After inspections on all the upgraded components every 25 hours, we had no issues. It sure is nice not to worry about my mechanics getting grease in all the pin point fitting on the Aerostar landing gear. Also, the famous grease stripe on the back of your shirt from the greasy flap tracks is no more. It’s much easier to keep everything clean and the dirt is not attracted to the excess grease on the gear.”

Jimmy is currently in the process of putting an Aerostar Super Star 700 back together that came from South Africa. He is planning on installing the complete greaseless Landing Gear Upgrade Kit (M1003) in this airplane as well. “We have the airplane apart and delivered in a container, so no better time than now to do the installation” stated Jimmy. I can’t wait to have both my airplanes completely greaseless”.

Speaking with Jimmy, he estimates about a week for a complete R&R for all three gear legs. Our estimate for the shop work involving teardown, removal of finishes, inspection, priming and painting plus bearing fitting, re-assembly and test is about two-to-three weeks.

So why do it? After all it makes good sense all around—no more discoloration from grease/oil streaks, no more worrying about the possibility of a seized joint and most important of all—less time in the hangar means more time in the air.



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