Five Consequences of Ignoring Landing Gear Trunnion Corrosion

April 2025

Corrosion ignored never stops!

Due to its location and exposure to the elements, landing gear is highly susceptible to corrosion. 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.

At Duncan Aviation, we want to advise you of a corrosive situation that can occur on all LJ aircraft, excluding the L45 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 landing gear trunnion corrosion:

1. Costs increasing because you may need to remove the wing and send it to the OEM for repair or replace the wing entirely.
2. Sanctions from the FAA for violating the maintenance manual, which requires that all corrosion be repaired.
3. Castings may need to be replaced, depending on how long the corrosion is ignored.
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 the trunnion castings, the wing will need to be de-mated and shipped to the OEM. 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, and months of downtime and at a dramatically lower 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.

If you have questions about this or other LJ technical issues, contact Trevor Bartlett, Airframe Technical Representative. For scheduling and pricing information, contact a Duncan Aviation Learjet Airframe Service Sales Representative.