AH-1S High-Survivable Transmission System

The objective of the work performed on this program was to demonstrate that the AH-1S main transmission system, modified with internal component improvements but without an emergency lubrication system, could operate for 30 minutes following the loss of lubrication. The internal component improvements were based upon work done under this program and work done under a previous Eustis Directorate contract, both conducted by Bell Helicopter Textron. Six different modified versions of the AH-1S transmission configuration were tested under this program. Four of the six transmission configurations had been run to failure previously and the results reported in USAAMRDL-TR-77-30. The loss-of-lube testing for the final two transmission configurations was conducted at 680 input horsepower (60 percent of maximum continuous power rating of the AH-1S) and 6600 input rpm. The first transmission configuration tested ran 25 minutes under loss-of-lube conditions before failure of the lower planetary stage. The second transmission configuration ran 54 minutes before failure of the lower planetary stage. Thus, the 30-minute loss-of-lube capability has been demonstrated for all transmission components. (Author) See also Rept. no. USAAMRDL-TR-77-30 dated Oct 77, AD-A047 558.