While flying Hueys for Uncle Sam the resident Bell rep advised the main transmission was good for either 30 or 60 minutes dry run, forget which. Had occasion to put it to the test and flew one for 15 minutes minus oil. Maintenance arrived fixed the problem (blown filter seal), filled with oil and they
(not me) flew it home.
The certification requirement for dry run capability is contained in FAR 29.927, the relevent portion being
(c) Lubrication system failure. For lubrication systems required for proper operation of rotor drive systems, the following apply:
(1) Category A. Unless such failures are extremely remote, it must be shown by test that any failure which results in loss of lubricant in any normal use lubrication system will not prevent continued safe operation, although not necessarily without damage, at a torque and rotational speed prescribed by the applicant for continued flight, for at least 30 minutes after perception by the flightcrew of the lubrication system failure or loss of lubricant.
It is an uneviable position to be in should you have knowledge of the requirement, for you are presented with the dilemma do I follow the checklist and toss it in the water in sea conditions which make survival problematic, or take a punt and continue flight (SHORT) to a known safe haven (safe haven being defined as calmer water (lee side of ship perhaps), beach etc etc).
PS: A T-53-13 will run at take off power for 2 minutes minus oil. Thanks Mr Lycoming
