MAULE AEROSPACE TECHNOLOGY, INC.
MAINTENANCE MANUAL
FOR
MT-7-420
9/02
3
Emergency
Mil-G-5572F, Aviation Gasoline, all grades (aircraft boost pump on; maximum
of 6 hours operation per overhaul period of turbine through an engine operat-
ing range of idle to 90% maximum SHP.)
CAUTION:
MIL-G-5572 fuel containing tricresylphosphate (TCP) additive shall NOT be
used.
Cold Weather:
To assure consistent starts below 4
°
C (40
°
F), the following fuels may be
necessary: MIL-T-5624, grade JP-4 ASTM D-1655, Jet B AVGAS/Jet A,
Jet A1, or JP-5 mixture (Refer to Cold Weather Fuels, para 2-48, of Allison
250-B17 Engine Series Operation and Maintenance Manual for mixing/use
of cold weather fuel.)
NOTE:
Jet A, A1, JP-8 or JP-5 fuels are not restricted from use at ambient tempera-
tures below 0
°
F (-18
°
C); however, special provisions for starting must be
made. (Refer to the Aircraft Flight Manual.) Prolonged and uninterrupted op-
eration with only AVGAS mixture will induce lead buildup on turbine parts.
This lead buildup can cause a gradual power reduction; consequently, this
AVGAS mixture should be used only for cold weather operation. During op-
eration with normal Jet A type fuel, the lead will slowly dissipate.
Engine Oil Specification:
The 250 Series engines are qualified and certified for use with MIL-L-7808 and subse-
quent, and MIL-L-23699 series lubricating oils. The vendor brands of MIL-L-7808 and MIL-L-
23699 series lubricating oils, which have been engine tested and accepted for use in the
Model 250 engine, are listed in the Approved Oils paragraph of Allison 250-BI7 Engine Series
Operation & Maintenance Manual. Refer to para 1-73, Cold Weather Lubrication for the type
of oil recommended at specific ambient temperatures.
NOTE:
Because of availability, reduced coking and better lubricating qualities at higher
temperatures, MIL-L-23699 oils are preferred for use in Model 250 engines. (Except
for extremely cold weather operation, as indicated below).
Cold Weather Lubrication. The types of oil recommended at specific ambient temperatures
are as follows:
Ambient Temperature.
Oil Type
0
°
C (32
°
F) and above
MIL-L-23699, preferred
0
°
C (32
°
F) to -40
°
(-40
°
F)
NM-L-23699 or MIL-L-7808G
-40
°
C (-40
°
F) and below
MIL-L-7808G only
