Main Landing Gear Alignments
What aircraft, if any, have adjustments for aligning the main landing gears or trucks along the fore and aft axis.?
Do any main wheels have Toe in/out and or Camber.?
Some twin nose wheels appear to have camber and may be toe-in to provide some self centering or anti shimmy.
There have been a few with steerable main wheels such as that on the B-52 BUFF to cater for X-wind landings and perhaps take-offs.
Volume
14th Nov 2005, 05:52
Interesting question, I was dealing with this problem two or three years ago, when a journalist tried to make up a big story about aircraft landing gear misalignment.
Design of the landing gear is differing a lot in this respect, some aircraft allow for adjustment by selecting shims in the toque link connection, some have excentric spherical bearings in the main landing gear attach points, and some have simply nothing to adjust. In some maintenance manuals this adjustment procedure is included, for others adjustment is just done once during manufacturing and never touched again.
Highest misalignment measured during this project was 2.5 degrees, as the journo was very familiar with cars, he thought this was a dangerously high value, and landing gears will fall of airplanes soon all over the world, due to the additional loads ;)
It was interesting to see, that some aircraft manufacturers manage to produce surprisingly accurate landing gears (misalignment below 1 minute on all four aircraft checked) without adjustment possibility, while others that have an adjustment provision, produce aircraft with more than 2 degrees misalignment.
Thinking of typical aircraft landing gear side loads due to x-wing landings or fast taxi, the additional side load due to the misalignment is neglectable. The effect on tire wear is remarkable. When we visited some operators, the mechanics knew exactly which aircraft would have the highest misalignment, simply because it has the lowest tire life in their fleet, and they were right everytime :D