81-03-02 DETROIT DIESEL ALLISON: Amendment 39-4026. Applies to Model 501-D13, 501-D13A, 501- D13D, 501-D13E, 501-D13H engines equipped with 1st stage turbine wheel, Part Number 6851511; 2nd stage turbine wheel, Part Numbers 6847142 and 6876892; 3rd stage turbine wheel, Part Numbers 6845883 and 6849743; and 4th stage turbine wheel, Part Number 6876468.
Compliance is required as indicated. The following limits were established by manufacturer conducted tests, and analyses and are being imposed to preclude the possibility of catastrophic wheel failures which could occur subsequent to the intervals noted. The schedule for wheel removal is as follows and is a function of the wheel spline interference fit:
TURBINE WHEEL
CYCLIC LIMITS
(Spline Fit 0.0000-0.0009T)
CYCLIC LIMITS
(Spline Fit 0.001-0.0025T)
Stage 1
24,000 cycles
30,000 cycles
Stage 2
18,000 cycles
26,000 cycles
Stage 3
16,000 cycles
22,000 cycles
Stage 4
18,000 cycles
26,000 cyclesIt is the operator's responsibility to obtain wheel-to-shaft spline fit data from their overhauler to determine which fit applies to their respective turbine or turbines. Only wheels that have conformed to a .001T minimum fit throughout their entire utilization history qualify for the higher cyclic limits above.
NOTE: If any turbine wheel has more than the number of cycles appropriate for its retirement as shown in this table above on the effective date of this AD, it must be replaced prior to accruing 100 additional cycles.
The above cyclic limits are in addition to the following existing hourly life limits which are specified in Detroit Diesel Allison Commercial Service Letter CSL-120.
TURBINE WHEEL
LIFE LIMIT, HOURS
Stage 1
9700
Stage 2
11000
Stage 3
9900
Stage 4
11000
Upon request of the operator, an FAA maintenance inspector, subject to approval of the Chief, Engineering and Manufacturing Branch, Great Lakes Region, may permit alternate actions which provide equivalent levels of safety if the request contains substantiating data to justify them.
This amendment becomes effective January 28, 1981.