MIL-DTL-6162C
3.4.6.3 Liquid cooling - Type IV. Unless otherwise specified, MIL-PRF-23699 turbine oil shall be used as the
cooling fluid. The generator shall provide an integral pump for oil circulation. The associated specification sheet
will provide oil temperature limits, flow, pressure, and airframe coordination requirements.
3.4.7 Rating charts. (See 4.6.1).
3.4.7.1 Altitude rating chart. The machine manufacturer shall supply altitude rating charts (2000-hour life
except for brushes) of safe allowable ratings for generator operation in blast-cooled and, where applicable,
self-cooled operating conditions. This chart shall be in the general form of Figure 7. The spacing and number of
lines shall be selected to provide a readable accuracy of 90 percent. The rating charts shall be prepared for the
following minimum range of parameters:
Generator pressure drop
0 to 4 times rated
- 40° to 20° C (-40° to 68° F) above maximum rated
Air inlet temperature
Pressure altitude
sea level to 65,000 feet
Generator speed
minimum speed for regulation to maximum speed for regulation
3.4.7.2 Starter speed-torque characteristics. For starter-generators, the manufacturer shall furnish a
speed-torque characteristic chart. This chart shall be in the general form of Figure 8 with both current and voltage as
parameters. The spacing and number of lines shall be selected to provide a readable accuracy within 10 percent. The
charts shall be prepared for the following minimum range of parameters:
Terminal volt
0 to nominal starting voltage (24 or 48V)
Current
0 to 1100 amperes (A)
Speed
0 to no load rpm
Where the starter-generator no load speed would be destructive, the test shall be interrupted when starter attains
speed specified for continuous generator operation.
3.4.7.3 Equalizing voltage-temperature characteristics. The machine manufacturer shall supply a chart of
equalizing voltage versus cooling temperatures for temperatures between 5° C (41° F) and 45° C (113° F) when the
machine is operated as a generator at rated load and continuous operating speed.
3.4.8 Operating position. The machine shall be designed to operate in any position.
3.4.9 Maintenance operation. Starter generators are required to crank the aircraft engine during engine service
and maintenance operation. This operation consists of a start cycle, which is aborted when the engine reaches
ignition speed. The engine is allowed to coast to rest and the cycle repeated. A minimum of five consecutive cycles
is required. The residual field voltage shall not be reversed or diminished below the specified minimum as a result of
this operation.
3.4.10 Cooling air port screens. The machine shall be equipped with screened cooling-air exhaust ports to
prevent entry of foreign objects. The size of the openings in the screen shall be such that a ¼-inch diameter ball or
rod will not pass through (see 4.6.1).
3.4.11 Bonding. The frame structure of the machine shall be so assembled that there will be a continuous, low
impedance path from the anti-drive end-bell to face of mounting flange. The direct current resistance end-bell to
mounting flange shall not exceed 0.001 ohm. The area normally covered by mounting nuts shall be free from any
insulating type of surface treatment (see 4.6.1).
3.4.12 Dimensions. The machine shall conform to the dimensions as shown in the associated specification
sheet or drawing listed in the QPL (see 4.6.1 and 6.3).
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