MBA has received the Transport Canada and FAA STC’s for the Bonanza and Baron Nose Gear Door Hinge Upgrade kit. This upgrade kit is a $200 fix for a problem that most owners of these aircraft have had or will have.
The OEM design uses a steel bushing in an aluminum hinge arm. The steel wears into the aluminum, enlarging the hole and resulting in play within the joint that continually increases with time and cycles. Previously, the only solution was a PMA'd bush of increased diameter. The problem however does not go away. Steel on aluminium does not wear well and the fix only begins another cycle of wear.
MBA has developed a fix that is very similar to the design of its popular main gear door hinge upgrade kits. The probability of worn hinge arms is so high however, that MBA assumes an oversize bush will be needed. MBA supplies two drills to progressively drill out the hinge arm to a new diameter where the AeroTough bushing can be pressed in with a proper interference fit. If there is to be any wear in the future it will be on the inside diameter of the bushing, not on the hinge arm.
The AeroTough GF polymer material needs no lubrication. The lubricant is built into the polymer. MBA has also CNC machined the stainless steel sleeve which runs against the AeroTough bush. Included in the kit is all the hardware needed for the installation.
If the hinge arms have already been drilled out past the 0.312" bore required for the AeroTough GF bushing, new arms will be required.
To check for wear on the nose gear doors of your aircraft, lift up and down vertically at the front of the door, checking for play you can feel. Don't confuse this with the lost motion in the door closing linkage which would be in the direction of the arc of operation.
Out of 30 aircraft surveyed by MBA staff last year at Oshkosh, 23 exhibited nose gear door hinge bushing wear. That was only checking the forward bushing. Typically the rear bushing wears even more.
MBA Nose Gear Door Hinge Upgrade Kits are available from MBA or from Aircraft Spruce. No installation kit is required.
About Marsh Brothers Aviation
Marsh Brothers Aviation is part of the Thomson-Gordon Group, a Canadian manufacturer of bearings, seals and engineered mechanical components for diverse global markets since 1911. This connection provides access to superior engineering, manufacturing and state-of-the-art R&D facilities that encourage innovation and the delivery of high performance products and quality service. Marsh Brothers Aviation brings the expertise of the Thomson-Gordon Group to the aircraft industry with a focus on the innovative development and supply of high performance parts and service, initially to general aviation aircraft, but with the intention to expand into the transport category aircraft market.For further information: