AD 48-01-01

48-01-01 DOUGLAS: Applies to C-54 and DC-4 Aircraft.

Because of cracking and failure in the locking groove of Goodyear Model 20DHBM wheels, Assembly No. 530402-M, resulting from the use of the old one-place flange and lock ring, the following must be accomplished:

I. Not later than the next scheduled inspection at which necessary facilities are available, and at each succeeding No. 3 inspection until II is accomplished:

(1) Remove the wheel-retaining flange from all wheels which are used with , or ever have been used with, the one-piece retaining flange P/N 511033 or 530405-M and lock ring P/N 511051-1.

(2) Clean and etch the wheel lock ring groove and carefully inspect to determine if any cracking has started. Remove from service all wheels found to be cracked.

(3) Measure the diameter of the lock ring groove at the locking surface. The nominal diameter is 0.440 inch + 0.002 inch. When the groove has worn to more than 0.500-inch diameter and less than 0.563-inch, remove wheel from service until it has been reworked to provide a true radius in the outer side of the groove and the thrust surface is made parallel to the end of the wheel. This radius should be 0.220 inch + 0.001 inch. Wheels reworked in this manner must be inspected at each 500 hours or the closest major inspection period thereto. Remove from service any wheels in which the groove has worn to a diameter equal to or exceeding 0.563-inch.

II. To be accomplished not later than August 1, 1948.

Remove from service all one-piece flanges and lock rings and replace by two-piece flange P/N 530735-M and studs P/N 511284-6.

(Goodyear Service Bulletin No. 1 covers this same subject.)