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| ![]() MIL-F-8615D
3.6.10 Lubrication. Fuel system components shall function satisfactorily
without the need for lubrication other than the fuel in which it operates
during its useful service life. Wherever a lubricant is required (such as a
gear assembly) it shall be a sealed unit and shall not require relubrication
between overhaul periods.
3.6.11 Overspeed. Components containing rotating members which can over-
speed for any reason shall have a self-contained speed regulator and shall
also be designed to prevent propagation of any failure outside of the housing.
3.7 Performance. All necessary specific performance requirements must be
provided by the item specification. The following paragraphs shall be used
as guides in preparing the item specification requirements, but they do not
necessarily contain all the required performance parameters.
3.7.1 Calibration. All critical calibration points shall be specified, such
as, flow rates, pressure schedules, pressure drop (or rise), fluid level,
response adjustments, or power requirements.
3.7.2 Altitude. Fuel system components shall deliver full required perform-
ance at all altitude levels, and during changes in altitude. If performance
is required to be insensitive to altitude, the specification shall so state.
3.7.3 Acceleration. The required performance during changes in speed or
changes in direction shall be specified.
3.7.4 Gravity force. The component performance during periods of inverted
flight or changes in the effective gravity force, shall be in accordance with
system requirements as stated in the detail specification.
3.7.5 Endurance. In general, components whose operational life is time
dependent shall have a minimum endurance of 1,200 hours between overhaul
periods. For components whose operation is intermittent, and are operated
10 times or more per flight or a component whose failure can impose a hazard
shall have a minimum endurance of 100,000 cycles. For components that operate
less frequently, and are not safety critical, the required endurance shall be
10,000 cycles. The endurance test shall encompass all operational conditions
from sea level to maximum altitude, including high and low temperature exposure
as well as dry operation (without fuel).
3.7.6 Water and ice. Water (or ice) shall not be a cause of a fuel system
component failure. The water may come from any available source, such as
free or dissolved water in the fuel, vapor in a bleed air system, clouds,
rain, etc. Any fuel system component whose failure, due to water (or ice)
could prevent transfer of fuel, or could cause a buildup of pressure, either
positive or negative, in excess of design allowances, shall demonstrate its
capability to satisfy aircraft system requirements in the presence of water,
either in the fuel or in the surrounding atmosphere.
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