TM 1-1510-224-10
Section III. POWER LIMITS
5-13. ENGINE LIMITATIONS.
Observe
limitations
found
in
table
5-1
during
operation of this aircraft, equipped with two Pratt and
Whitney of Canada, Ltd, PT6A-67 engines. Each
column is a separate limitation. The limits presented do
not necessarily occur simultaneously. Whenever
operating limits are exceeded, the pilot should record the
value and duration of the condition encountered, in the
aircraft log. Operation of the engines is monitored by
instruments, with reference to the operating limits
marked on the face of each instrument.
CAUTION
Engine operation using only the
engine-driven
fuel
pump
without
boost pump fuel pressure is limited
to 10 cumulative hours. All time in
this category shall be entered on DA
Form 240813-1 for the attention of
maintenance personnel.
Table 5-1. Engine Operating Limitations
OPERATING
TORQUE
MAXIMUM
GAS
PROP
OIL
OIL
CONDITION
%
OBSERVED
GENERATOR
RPM
PRESS
TEMP
(1)
TGT°C
RPM N
1%
N2
PSI
°C
(10)
(2)
(3)
STARTING
--
1000(4)
--
--
200
-40 (min)
(max)
LOW IDLE
--
750(5)
62 (min)
1000 (min)
60 (min)
-40 to 110
HIGH IDLE
--
--
(6)
1000 (min)
--
--
TAKEOFF (5 MIN.)
100
840
104
1700
90 to 135
10 to 110
MAX. CONT.
100
830
104
1700
90 to 135
10 to 105
MAX. CRUISE and
(7) (9)
810
104
(9)
90 to 135
10 to 105
MAX CLIMB
(9)
810
104
(9)
90 to 135
10 to 105
NORMAL CRUISE and
(7) (9)
800
104
(9)
90 to 135
10 to 105
NORMAL CLIMB
(9)
800
104
(9)
90 to 135
10 to 105
MAX REVERSE
75
760
88
1650
90 to 135
10 to 105
TRANSIENT
138(8)
870(8)
104
1870(8)
40 (min)
-40 to 110
200
(max) (8)
NOTES:
The limits presented do not necessarily occur simultaneously. Whenever
operation limits are exceeded the pilot will record the value and duration of the
condition encountered on DA Form 2408-13-1.
(1)
Torque limit applies within range of 1000 to 1700 propeller RPM (N
2
). Below 1000 RPM, torque is limited to 54%.
(2)
An engine oil temperature of 74 C to 80 C is recommended.
(3)
Oil temperature limits are -40 C to 105 C. However, temperatures of up to 110 C are permitted for a maximum
time of 10 minutes.
(4)
These values are time limited to 5 seconds
(5)
High TGT at ground idle may be corrected by reducing accessory load and/or increasing N
1
RPM.
(6)
At approximately 72% N
1.
(7)
Cruise torque values shall be set per Chapter 7. Operating engines during cruise at higher torque values than
those listed in chapter 7 will reduce engine life.
(8)
These values are time limited to 20 seconds.
(9)
Torque limited to 94% when operating at 1500 RPM (N
2
). Torque limited to 83% when operating at 1700 RPM
(N2)-
(10)
Oil Pressures below 90 PSI are undesirable. Under emergency conditions, a lower oil pressure limit of 60 PSI is
permissible at reduced power, not to exceed 54% torque.
BT00191
5-8
