NATOPS Ch. 4

Question 1

Exceeding Operating Limitations

Answer 1

Anytime an operational limit is exceeded, an appropriate entry shall be made on a Maintenance Action Form (MAF). The entry shall state what limits were exceeded and include range, duration, and any additional data that would aid maintenance personnel.

The flight display’s digital readout will display “XXX” in red when a TGT or torque limit is exceeded.

If a limit is exceeded to the extent that a red “XXX” is indicated, the crew shall land as soon as practicable.

Question 2

Engine Limitations

Answer 2

The engines are limited by Ng, Np, TGT, oil pressure, and oil temperature (Figure 4-1). Specified temperature limits ensure that the engines are operated at internal temperatures that will not shorten the service life expectancy of engine
components.

Question 3

Engine Starter Limitations

Answer 3

Engine starter limitations are presented in Figure 4-2. A start cycle is defined as starter initiation, acceleration of the
output drive, and starter dropout. A 60-second delay between start attempts is required any time a start is aborted,
except during emergencies.

Question 4

Engine Start Limitations

Answer 4

1. The single- and dual-engine start envelopes are presented in Figure 4-3. For crossbleed starts, the receiving engine shall be at or above 24 percent Ng prior to advancing PCL to IDLE.
2. Engine start with the main rotor blades or tail rotor pylon folded is prohibited.
3. The start TGT limit is 851 °C until idle speed is attained.

Question 5

Engine Idle Limitations with Gust Lock Engaged

Answer 5

Engine operation with gust lock engaged is prohibited.

Question 6

Turbine Gas Temperature (TGT)

Answer 6

0-810 °C Continuous Green

810-851 °C 30 minutes Yellow

851-878 °C 10 minutes Red

878-903 °C 2.5 minutes Red

903-949 °C 12 seconds Red

949 Maximum Red

Question 7

Power Turbine Speed Np

Answer 7

<96% Avoid Red

96 to 105% Continuous Green (Yellow above
101%)

105 to 117% 20 seconds Yellow

117 to 120% 12 seconds Yellow

120% Maximum Red

Caution: During engagement, extended operations in the 20 to 40% and 60 to 75% ranges may cause engine damage.

Question 8

Main Rotor Speed (Nr)

Answer 8

<96% Avoid Red

96 to 101% Continuous Green

101 to 120% Precautionary Yellow

120% Maximum Red

> 120% 123%, Maximum for
FCF only Red

127% Overspeed Latch Red

Question 9

Dual-Engine Torque (TRQ) <80 KIAS

Answer 9

0 to 120% Continuous Green

120 to 144% 10 seconds Yellow

144% Maximum Red

Question 10

Dual-Engine Torque (TRQ) >80 KIAS

Answer 10

0 to 106% Continuous Green

106 to 127% 10 seconds Yellow

127% Maximum Red

Note: Dual Engine Torque Limits apply when both engines are above 65% torque.

Question 11

Single-Engine Torque

Answer 11

0 to 135% Continuous Green

135 to 144% 10 seconds Red

144% Maximum Red

Question 12

Gas Generator Speed

Ng

Answer 12

0 to 102.2% Continuous Green

> 102.2 to 106% 2.5 minutes Yellow

> 106 to 107% 12 seconds Red

107% Maximum Red

Question 13

Transmission
Temperature (XMSN
T)

Answer 13

-50 to 105 °C Continuous Green

105 to 120 °C Precautionary Yellow

120 °C Maximum Red

Question 14

Transmission Pressure

XMSN P

Answer 14

20 psi Minimum Red

20 to 30 psi Idle and transient Yellow

30 to 65 psi
(45 to 60 psi in level flight) Continuous Green

65 to 130 psi Precautionary Yellow

130 psi Maximum Red

Question 15

Engine Oil Temperature (ENG OIL T)

Answer 15

-50 to 135 °C Continuous Green

135 to 150 °C 30 minutes Yellow

150 °C Maximum Red

Question 16

Engine Oil Pressure (ENG OIL P)

Answer 16

22 psi Minimum Red

22 to 26 psi Precautionary Yellow

26 to 100 psi Continuous Green

100 to 120 psi Precautionary Yellow

120 psi Maximum Red

Note: Normal idle range is 22-55 psi

Question 17

Engine Start (OAT/Starter Engaged/Starter Disengaged)

Answer 17

<16 °C

First Cycle 60 Seconds
Second Cycle 60 Seconds
Third Cycle 60 Seconds
Fourth Cycle 30 Minutes

16 to 52 °C

First Cycle 60 Seconds
Second Cycle 30 Minutes

Question 18

Engine Motor (Ignition OFF) (OAT/Starter Engaged/Stater Disengaged)

Answer 18

Any temperature

2 minutes engaged, 5 minutes disengaged

2 minutes engaged, 30 minutes disengaged

Notes:

1. A start cycle is defined as starter initiation, acceleration, and dropout.
2. Times for motoring are cumulative within a 5-minute period.

Question 19

Minimum planned fuel on landing

Answer 19

Minimum planned fuel on landing shall be no less than 600 pounds.

Question 20

APU Limitations

Answer 20

The APU is not intended for routine in-flight use. Operation of the APU in flight shall be limited to essential operations only. Acceptable in-flight use includes emergency procedures, single-engine training, practice autorotations, and powering the ECS during extreme temperature operations.

Question 21

Transmission Limitations

Answer 21

The transmission is limited by Nr, torque, oil pressure, and oil temperature (Figure 4-1). Operation is governed by whichever limit is reached first.

Note: Engine torques over 150% are displayed as red “XXX.”

Question 22

Transmission Oil Temperature Limitations

Answer 22

During any operating condition, no maintenance action is required if main transmission oil temperature is in the precautionary range continuously for 5 minutes or less.

Prolonged Hovering in hot weather, 86 °F (30 °C), may cause main transmission oil temperature to rise into the
precautionary range. Operation in the precautionary range for less than 30 minutes during any one flight under this
condition is acceptable and no maintenance action is required.

Question 23

Transmission Oil Pressure Limitations

Answer 23

During steady-state level pitch attitudes (i.e., level flight), the transmission oil pressure should be 45 to 60 psi. The following conditions do not constitute an immediate emergency situation, but may be indicative of a degraded
lubrication system. Any discrepancy shall be documented on a Maintenance Action Form (MAF).

1. Steady pressure outside of 45 to 60 psi, but within the normal limits of 30 to 65 psi.
2. Fluctuations not to exceed a range of 10 psi, within the normal limits of 30 to 65 psi.

During transient pitch or steady-state nose-high pitch attitudes (autorotations, downwind hovering, rearward flight,
slope-up landings, etc.) transmission oil pressure fluctuations (including momentary fluctuations below 30 psi and
transient drops below 20 psi for up to one second) are acceptable. Operating with pressure fluctuations below 30 psi shall be limited to 30 minutes.

During rotor engagement, a zero oil pressure indication may indicate a no-oil-flow condition through the oil
lubrication system. Operating with a no oil pressure indication shall be limited to less than 1 minute and shall be
documented on a Maintenance Action Form (MAF).

Question 24

Rotor Engagement and Disengagement Limitations

Answer 24

Maximum wind velocity for rotor engagement or disengagement is 45 knots from any direction.

Question 25

Airspeed Operating Limits

Answer 25

Airspeed is limited as follows:

1. Maximum (Vne) — 180 KIAS.
2. Maximum as limited by blade stall — Refer to Figure 22-3.
3. Sideward/rearward flight — 35 knots.
4. Autorotation — 100 KIAS.
5. Boost off — 140 KIAS.
6. SAS 1 and SAS 2 inoperative in IMC — 125 KIAS.
7. Either PRI SERVO PRESS caution — 125 KIAS.
8. Searchlight in fixed position other than stowed — 160 KIAS.
9. Searchlight in transition — 100 KIAS.
10. Dome at or above trail (cable extended 10 feet, dome approximately 6 feet below aircraft) — 70 KIAS, 45°
    AOB. Dome below trail — 70 KIAS, 15° AOB.
11. Cabin door opening/closing — 60 KIAS.

Note
• With cabin door open, uncoordinated flight should be avoided.
• With MTS installed, failure to maintain balanced flight below 90 KIAS in descents over 1,000 fpm will result in inaccurate and erratic airspeed indications.

Question 26

Hovering Limitations

Answer 26

1. Prolonged rearward flight and downwind hovering should be avoided to prevent accumulation of exhaust fumes in the helicopter and heat damage to the window on an open cabin door.
2. Hovering turns at a rate in excess of 30° per second.
3. Dipping sonar operations at altitudes other than 70 feet. Deviation of aircraft hover altitude from 70 feet while transducer assembly
   is entering or exiting the water may result in damage to the dipping sonar equipment due to electrostatic discharge.
4. Do not tow the transducer in the water above 8 KGS with array folded and 4 KGS with array unfolded.

Caution: Exceeding 8 KGS with array folded or 4 KGS with array unfolded may cause TA cable separation.

Note: Towing is defined as the cable contacting the funnel. Aircraft ground speed may be greater than 8 KGS (folded) or 4 KGS (unfolded) provided the cable is not in contact with the funnel.

Question 27

AOB Limitations

Answer 27

Bank angles shall be limited to the following:

1. Normal operations — 45°.
2. Operations above 10,000 feet DA — 30°.
3. Either PRI SERVO PRESS caution — 30°.
4. Boost off flight — 30°.

Question 28

Altitude Limitation

Answer 28

Maximum operating density altitude is 13,000 feet.

Question 29

Prohibited Maneuvers

Answer 29

The following maneuvers are prohibited:

1. Aerobatic flight.
2. Practice full-autorotation landings.
3. Intentional approaches into or inducement of retreating blade stall.

Question 30

Rotor Brake Operating Limitations

Answer 30

Maximum rotor speed for rotor brake application is 76 percent Nr. Routine rotor stops shall be made between 30 and 50 percent Nr. Routine rotor brake stops should be limited to 180 psi to extend service life.

Question 31

Blade, Pylon, and Stabilator Fold and Spread Limitations

Answer 31

Maximum wind velocity for blade fold and spread is 45 knots from any direction. Following a complete blade fold and spread cycle, allow a 10-minute cooling period before commencing another blade fold and spread evolution. A complete blade fold and spread cycle is defined as a full spread evolution followed immediately by a full fold
evolution or vice versa.

Maximum wind velocity for tail pylon or stabilator fold/spread operations is 45 knots from any direction.

Question 32

Landing Limitations

Answer 32

The following landing limitations apply:

1. Maximum rate of descent for level terrain shall not exceed 720 fpm for gross weight less than 19,500 pounds and 480 fpm for gross weight above 19,500 pounds.
2. Maximum rate of descent for sloped terrain shall not exceed 360 fpm.
3. Maximum touchdown speed shall not exceed 75 KGS with tailwheel locked and 20 KGS with tailwheel
   unlocked.
4. Maximum ground taxi speed is 40 KGS. If the shimmy damper is not installed or inoperative, maximum ground taxi speed is 20 KGS.
5. Slope landing limitations:
   a. 9° nose-up slope.
   b. 12° cross-slope.
   c. 6° nose-down slope.

Note: A low-frequency oscillation may occur when landing nose-down on a slope with the cyclic near the aft stop.

6. Downwind landings should be avoided.

Question 33

Windows

Answer 33

Windows shall not be installed or removed in flight, except during actual aircraft emergencies

Question 34

Aircraft Operating Gross Weight Limitations

Answer 34

The maximum operating gross weight is 23,500 pounds. The maximum launch and recovery gross weight for aviation ships is 23,500 pounds. The maximum launch and recovery gross weight for air-capable ships and
amphibious assault aviation ships is 22,500 pounds.

Question 35

External Load Weight Limitations

Answer 35

The maximum weight that may be suspended from the cargo hook is 6,000 pounds. The maximum weight that may be suspended from the rescue hoist is 600 pounds.

Question 36

Minimum Aircraft Equipment for Night Flight Over Water

Answer 36

The following operable equipment is required for night flight over water:

1. LAWS.
2. Altitude hold (RAD ALT or BAR ALT).

Question 37

Minimum Aircraft Equipment for Flights into Forecast or Known Icing Conditions

Answer 37

Helicopters equipped with operable anti-ice and blade de-ice equipment are permitted flight into forecast or known trace or light icing conditions. All installed anti-ice/de-ice equipment (windshield, engine, rotor) shall be operational
prior to flight. Helicopters not equipped with operable blade de-ice equipment are prohibited from flight into forecast or known icing conditions (ambient temperatures of 5 °C or below in visible moisture). Refer to Chapter 14 for
specific information on flight in icing conditions.

The following icing limitations apply:

1. Flight into known icing conditions without de-ice equipment is prohibited.
2. Flight into forecasted or known moderate or severe icing conditions is prohibited.

Question 38

Minimum Equipment for Passengers

Answer 38

Except in emergency situations, helicopter emergency egress lighting system (ADHEELS and IHEELS) shall be
operational for all overwater flights requiring passengers/non-aircrew in the cabin.

For passenger and aircrew seating requirements, refer to CNAF M-3710.7 Chapter 7.

Question 39

Temperature Limitations

Answer 39

Operations at temperatures below -40 °C (-40 °F) or above 60 °C (140 °F) are prohibited.

Question 40

Backup Hydraulic Pump Limitations

Answer 40

During prolonged ground operation of the backup pump with the rotor system static, the backup pump is limited to the operating times shown in Figure 4-6 to prevent hydraulic fluid overheating.

33 to 38 °C 24 mins operating time 72 mins cool down time
39 to 60 °C 16 mins operating time 48 mins cool down time

Question 41

APU Operating Limitations

Answer 41

To prevent APU overheating, APU operation at ambient temperature of 43 °C and above with engine and rotor
operating is limited to 30 minutes. With engine and rotor not operating, the APU may be operated continuously up to an ambient temperature of 51 °C.