Five Consequences of Ignoring Landing Gear Trunnion Corrosion

October 2017

Corrosion ignored never stops!

Due to its location and exposure to the elements, landing gear is highly susceptible to corrosion. And corrosion, even in small amounts, will not stop growing unless it is effectively removed. If left unattended, landing gear corrosion can grow and jeopardize the functionality and airworthiness of the unit leading to expensive repairs or the premature removal of components.

As a Bombardier Learjet* Authorized Service Facility, I want to advise you of a corrosive situation that can occur on all Bombardier Learjet aircraft, excluding the Learjet 45* series. These aircraft are susceptible to corrosion in the sockets for the main landing gear forward trunnion pins on the bottom side of the wing. Corrosion in this area is serious if left unattended, with the potential to cause cracks in the weakened casting and eventual failure resulting in a potential gear collapse.

Five consequences of ignoring Bombardier Learjet (non 45 series) landing gear trunnion corrosion

1. Increased repair costs requiring the sending of the wing to the OEM for repair or even complete wing replacement.
2. FAA violations for not following the maintenance manual, which requires the repair of all corrosion.
3. If corrosion is ignored for too long, the castings will have to be replaced.
4. Corrosion can spread into the adjacent spar, which translates into a longer downtime and more money to replace the spar, if not scrapping the entire wing.
5. Catastrophic failure of the Main Landing Gear socket resulting in a takeoff, landing or taxi incident leading to injury or loss of life.

Two solutions to trunnion casting corrosion

Replace Trunnion Castings. To replace trunnion castings, the wing will need to be de-mated and shipped to the OEM in Wichita, KS. There it will be placed in the production wing fixture to remove the upper skin and replace the trunnion castings. Depending on the demand for the fixture, we have seen downtimes as long as six months and at a significantly high repair cost.

Remove Corrosion from Trunnion Casting. Without having to remove the wing, Duncan Aviation is able to remove the corrosion with an on-wing fixture that allows qualified airframe technicians to bore the trunnion and insert a bushing, while staying within allowable limits. This repair process generally takes only 5-7 days to complete, eliminating the need for wing removal, shipping, months of downtime and at a dramatically less overall cost.

(Trunnion bore: 1) with corrosion, 2) after reaming, 3) with bushing installed)

If there is sufficient Ground Support Equipment available at your location, this repair can be performed in your hangar.

You can read more about this innovative on-wing fixture in the Fall 2017 Duncan Debrief. If you have any questions about this or other Learjet technical issues, contact me at any time. For scheduling and pricing information, contact a Duncan Aviation Learjet Airframe Service Sales Representative.

*Trademarks of Bombardier Inc. or its subsidiaries.