Yesterday while cleaning bugs off my -9A I noticed the right main wheel pant was loose. I expected to find bolt in the axel nut to be loose but it was not. Further investigation revealed that the 4 bolts securing the brake caliper and the pant bracket to the U-403-PC, Brake Mount Flange, were in various stages of looseness, from very loose to slightly loose. My IA buddy figures the Nyloc nuts got pretty hot, being close to the brake rotor, soften the nylon that provides the friction to hold the torque, and allowed the nuts to back off. I replaced the Nylocs with steel locknuts which should prevent a repeat of the problem. The left wheel pant is still solid, but I will replace the 4 Nylocs next time I remove the pant. Note: This aircraft has 1005 hours and is 6 years old. Dan
