Scott 3200 Tailwheel Spindle Failure
Posted: Fri May 15, 2009 8:06 pm
TIC170A member Dennis Hoffman asked me to post about an incident that happened to him last weekend. Fortunately it happened on the ground at our home airport, just as he began to taxi out of parking, and there was plenty of help around to get the airplane back to his hangar. He had spare parts available to get the problem fixed the same afternoon.
The failure was in the spindle part of the Scott 3200 Bracket Assembly: The spindle cracked in half, which allowed most of the tailwheel to become detached from the airplane: This part has a grease fitting on the wide end, which has been removed. It's drilled axially down from the fitting, and transversely where the crack occurred. It also had a groove machined around its circumference, to help distribute grease to the working parts located between the bracked assembly and the fork: The transverse passage and the circumferential groove seem to have created a weak area in the spindle where the crack occurred. Dennis noticed that the spare part he had did not have the groove, and the transverse passage was smaller in diameter than on the part that broke. We guessed that his replacement part might have been a later revision than the one that broke, engineered to prevent this problem.
This might be something to be sure to inspect the next time you disassemble your tailwheel.
Best Regards,
John
The failure was in the spindle part of the Scott 3200 Bracket Assembly: The spindle cracked in half, which allowed most of the tailwheel to become detached from the airplane: This part has a grease fitting on the wide end, which has been removed. It's drilled axially down from the fitting, and transversely where the crack occurred. It also had a groove machined around its circumference, to help distribute grease to the working parts located between the bracked assembly and the fork: The transverse passage and the circumferential groove seem to have created a weak area in the spindle where the crack occurred. Dennis noticed that the spare part he had did not have the groove, and the transverse passage was smaller in diameter than on the part that broke. We guessed that his replacement part might have been a later revision than the one that broke, engineered to prevent this problem.
This might be something to be sure to inspect the next time you disassemble your tailwheel.
Best Regards,
John