Chapter 5 - Limitations

Question 1

Engine Oil Pressure (PSI) Limits

Answer 1

Minimum Pressure for N_G at Ground Idle - 5 psi

Minimum Pressure for N_G Between 80 to 95% - 35 psi

Minimum Pressure for N_G Equal to or greater than 95% - 50 psi

Normal Operation - 35-90 psi

Maximum for Contingency Power - 110 psi

Maximum for Cold Weather Starts - 150 psi

Engine oil pressure limitations (Table 5-1) are displayed digitally on the POWER TRAIN page by pressing key T6 (Figure 5-1). The displays appear in green when the pressure is 5 to 90 psi, change to yellow if the pressure is greater than 90 psi, and change to red when the pressure is less than 5 psi or greater than 110 psi.

Question 2

Engine Oil Temperature (°C) Limits

Answer 2

Maximum - 149° C

Engine oil temperature limits (Table 5-2) are displayed digitally on the POWER TRAIN page (Figures 5-1 and 5-2). The displays appear in green when the temperature is equal to or less than 149° C and change to red, with the respective ENG1 (2) OIL HOT caution displayed, when the temperature is greater than 149° C.

Question 3

Transmission Oil Temperature (°C) Limits

Answer 3

Maximum - 140° C

Combining, aft, and forward transmission oil temperatures limits (Table 5-3) are displayed digitally on the POWER TRAIN page (Figures 5-1 and 5-2). The displays appear in green when the temperature is less than or equal to, 140° C and change to red when the temperature is greater than 140° C with the respective COMB, AFT, or FWD XMSN OIL HOT caution displayed.

Question 4

Transmission Oil Pressure (PSI) Limits

Answer 4

Minimum at Ground Idle - 7 psi

Minimum at 100% N_R - 20 psi

Normal Operation - 20 to 90 psi

Engine 1, Engine 2, combining, aft, and forward transmission oil pressures limits (Table 5-4) are displayed digitally on the POWER TRAIN page (Figures 5-1 and 5-2). The displays appear in green when the pressure is equal to or greater than 20 psi and change to red when the pressure is less than 20 psi and N_R is equal to, or greater than 25%. An ENG1, ENG2, COMB, AFT, or FWD XMSN PRESS LO caution is displayed if the pressure in any transmission is less than 20 psi and N_R is equal to or greater than 25%. An ENG1, ENG2, COMB, AFT, or FWD XMSN PRESS HI advisory is displayed when the pressure in any transmission is greater than 90 psi.

Question 5

Hydraulic System (PSI) Limitations

Answer 5

Hydraulic system pressures and temperatures for the No. 1 flight boost system, No. 2 flight boost system, and utility hydraulic system are displayed on the Maintenance Panel (Figure 5-5). The respective No. 1 (No. 2) HYD FLT CONTR caution will be displayed when hydraulic pressure is less than approximately 1,800 psi.

Question 6

Rotor N_R (%) Limitations

Answer 6

Minimum transient power-on - 91%

Transient - 91 to 97%

Normal - 97 to 101%

Transient - 101 to 106%

Maximum transient power-on - 106%

Maximum during autorotation - 108%

Maximum transient - 111%

Rotor RPM (N_R) is displayed digitally on the INST page (Figure 5-1). If N_R is outside normal operating range, it will be displayed on the INST page and below the VSD/VSDH torque tape, (Figure 5-6). N_R limits are shown in Table 5-5. Should 108% N_R power-off be inadvertently exceeded, no entry need be made on DA Form 2408-13-1 unless the rotor system accelerates and exceeds 111.5 % N_R. Even though no action is required when N_R exceeds 108% power-off, but remains at or below 111.5 %, willful operation shall not be conducted in this range.

Question 7

INSTR/POWER TRAIN Page

Answer 7

Question 8

Cruise Guide Indicator

Answer 8

The Cruise Guide Indicator (CGI) (Figure 5-7) is displayed on the VSD. The scale is displayed with four color range bands; green, yellow, red and white. When the CGI TEST switch is moved from the center position to each test position, the pointer on the indicator should indicate within the white test band. The white test band indicates proper system operation. Refer to Section V for airspeed limits. Flight equal to or less than 98% N_R with an inoperative CGI is prohibited.

Question 9

Starting and Shutdown Limits

Answer 9

Refer to Figures 5-3 and 5-4 to determine rotor blade start-up and shutdown limits. The APU shall not be started with a tailwind in excess of 25 knots. Main engines shall not be started with a tailwind in excess of 10 knots. If it becomes necessary to shutdown in conditions outside the limits shown in Figures 5-3 and 5-4, the following precautions are recommended:

1. Aircraft should land in an area which is clear, as level as possible, and at least 300 feet away from any vertical obstructions, abrupt changes in ground terrain, trees, bushes, fences, etc.

2. Aircraft should be oriented such that the wind would be coming in at the left side. If the pilot is unsure of the wind direction after landing, a crew member should be dispatched beyond the rotorwash to make a true wind direction determination before the engines are secured.

Question 10

Flight Control Hydraulic Pressure

Answer 10

Low Limit - 2500 PSI

Normal - 2500 to 3200 PSI

High Limit - 3200 PSI

Question 11

Utility System Hydraulic Pressure

Answer 11

Low Limit - 2500 PSI

Normal - 2500 to 3500 PSI

High Limit - 3500 PSI

Question 12

Hydraulic System Temperature

Answer 12

Maximum - 120ºC

Transient - 95º to 120ºC

Question 13

Power Limits

CAUTION

Answer 13

​CAUTION

For Pre-mission Performance Planning, Intermediate Torque Available (30-Minute Operation) is the maximum power authorized for departure and arrival at or below 40 KCAS. Continuous Torque Available is the maximum power authorized for cruise 􀃀ight. Additional Gross Weight limits are contained in Chapter 7, Cruise Charts.

Question 14

Engine Temperature (PTIT) Limits

Answer 14

Maximum Continuous - 816° C

Maximum for not more than 30 minutes - 854° C

Maximum for not more than 10 minutes - 899° C

Maximum for not more than 2.5 minutes (Contingency Power) - 932° C

Maximum Transient for not more than 12 seconds (never exceed) - 943° C

The engine Power Turbine Inlet Temperature (PTIT) for both engines (Table 5-6) are displayed on the INST page (Figure 5-1). The digital display and tapes on the scale (Table 2-7) appear in green for temperatures equal to or less than 816° C, change to yellow when greater than 816° C to 932° C, and change to red when equal to or greater than 932° C. If the PTIT in either engine is equal to or greater than 816° C, the ENG1(2) 30M TMP advisory will be displayed (Table 2-7). If the PTIT in either engine is equal to or greater than 854° C, the ENG1(2) 10M TMP advisory will be displayed (Table 2-7). Should the temperature reach 899° C for 2 seconds or longer, the ENG1(2) 2.5M TMP advisory will be displayed (Table 2-7). The ENG1(2) advisory will be displayed before actually reaching contingency power, providing a 5° buffer to advise the pilot he is about to enter this range. A PTIT timer digital readout will be displayed on the INST page when an engine is operating in a time limited range. The readout will display the allowable time remaining in the current PTIT operating range. Refer to Table 2-3 through Table 2-12 for system limits.

Question 15

Contingency Power

Answer 15

Contingency power is only to be used during actual emergency conditions. Usage of contingency power up to 932° C PTIT is permissible for an unlimited number of occurrences, as long as each occurrence is 2 minutes 30 seconds or less. Transient power 932° to 943° C PTIT is not to be greater than 12 seconds. If PTIT in either engine is equal to or greater than 932° ENG 1(2) 12S TMP advisory will be displayed, also a ENG 1 (2) TEMP HI (CAUTION) will be displayed.

Question 16

Gas Generator (NG) Limits

Answer 16

Ground Idle Minimum - 50%

Maximum - 111%

Engine gas generator speed is digitally shown in green when NG is between 50 to 111%, changes to yellow when less than 50%, and changes to red when greater than 111%. Speeds and limits are displayed on the INST page (Figure 5-1, and Tables 2-3, 2-11, and 5-7).

Question 17

Power Turbine (NP) Limits

Answer 17

Maximum - 111.5%

A power turbine (NP) overspeed may exist, depending on power being used when 106% NR is exceeded. The maximum limit for power turbine (NP) is 111.5%. NP speeds and limits are displayed on the INST page (Figure 5-1, and Tables 2-3 and 5-8).

Question 18

Engine Overspeed

Answer 18

An NG overspeed exists when a speed of 111% NG is exceeded. An NG overspeed can cause over-temperature and/or over-torque. Refer to Table 2-11 for system limits.

Question 19

Engine Torque (TQ) Limits

Answer 19

Maximum Dual Engine - 100%

Maximum Single Engine - 123%

The display appears in green if TQ is equal to or less than 100%, changes to red when greater than 100%, dual engine operations, or red at 123%, single engine operation. A voice alert “TORQUE” will be triggered when torque is greater than 95% dual or single engine. Refer to Table 2-9 for additional system limits.

NOTE

Average torque is displayed on the VSD. Should an engine failure occur, the actual torque of the operating engine will be displayed. When the torque split between the two engines is greater than 10%, the value of the maximum TQ line on the INST page will change from 100% to 123%.

Question 20

Fuel Limitations

Answer 20

NOTE

JP8 + 100 is not considered “Emergency Fuel”. A DA Form 2408-13-1 entry will be made as described in Appendix C.

Only those fuels listed in Chapter 2 shall be used. Emergency fuel shall not be used for more than 6 hours cumulative time.

Question 21

Maximum Gross Weight

Answer 21

The maximum allowable operating gross weight is 50,000 pounds.

Question 22

Cargo Hook Limitations

Answer 22

The limits presented below are structural limitations only.

1. The structural limit of the forward and aft hook is 17,000 pounds each.

2. The maximum single load that can be suspended as a tandem load from the forward and aft hooks is 25,000 pounds.

3. The center cargo hook is limited to a maximum load of 26,000 pounds.

4. When a combination of internal and external loads are carried during the same flight and the external load exceeds 12,000 pounds, position the internal load forward of the utility hatch. This procedure should preclude encountering an excessively aft CG.

Question 23

Winch/Rescue Hoist Limitations

Answer 23

The rescue hoist is limited to a maximum load of 600 pounds. Refer to Chapter 4 for system configuration and operation.

The winch shall not exceed:

1. 3,000 pounds straight line pull.

2. 6,000 pounds, one pulley.

3. 9,000 pounds, two pulleys.

4. 12,000 pounds, three pulleys.

Question 24

Cruise Guide Indicator (CGI) Limits

WARNING

CAUTION

Answer 24

WARNING

Sustained operation in the red or yellow band on the CGI will cause damage to the rotor dynamic components (i.e., pitch housing, swashplate assembly, etc.) resulting in failure of parts, destruction of the aircraft, and injury or death to the crew.

CAUTION

Strict compliance with the airspeed limitations provided in Figures 5-8, 5-9, and 5-10 is required regardless of cruise guide operational status. In addition, adherence to in-flight cruise guide limitations shall be maintained.

Any excursion into the red or yellow band for more than 45 seconds requires an entry on the DA Form 2408-13-1. Provide the following information: Free Air Temperature (FAT), Pressure Altitude (PA), and Gross Weight (GW), Knots Calibrated Airspeed (KCAS), total time in the red or yellow band, and needle position within red or yellow band (i.e., lower half or upper half).

Care must be exercised during certain maneuvers when level flight airspeeds result in steady CGI indications at the upper end of the green band. Aggressive maneuvers such as decelerating turns and break turns will increase aerodynamic loading. Reduction in aerodynamic loading includes one or more of the following:

1. Lowering the thrust.

2. Reducing the severity of the maneuver.

3. Reducing airspeed.

To increase life expectancy of aircraft components, transient CGI excursions into the yellow and red bands should be minimized.

Question 25

Airspeed and Gross Weight Limitations With An Operative or Inoperative Cruise Guide Indicator

CAUTION

NOTE

Answer 25

1. Maximum crosswind or sideward flight is 45 knots.

CAUTION

A Dual FADEC primary channel failure may occur when rearward flight or a tailwind exceeds 40 KCAS. These conditions should be avoided.

NOTE

Aircrew should be alert to the potential for large engine torque oscillations during rearward flight operations.

2. Maximum airspeed in rearward flight is 45 knots.

3. Maximum tailwind for hover is 45 knots.

4. Maximum airspeed with the lower section of the cabin entrance door open and locked is 60 KCAS.

5. The rescue hatch door shall not be opened or closed above 90 KCAS.

6. The windshield wipers shall be off at airspeeds above 130 KCAS.

7. Upper section of the cabin entrance-ensure that airspeed is less than 100 KCAS before closing door in flight.

8. Left side Escape Hatch: do not install or remove hatch in forward flight.

Question 26

External Cargo Airspeed Limits

Answer 26

If a sling or hook should fail while carrying a tandem load, limit airspeed to a maximum of 60 KCAS.

Question 27

Longitudinal Cyclic Trim (LCT) Actuator Airspeed Limits

​NOTE

Answer 27

The airspeed operating limits chart (Figure 5-9), shows the maximum allowable airspeeds and gross weights with either LCT fully retracted. Do not manually extend the LCT beyond the GND position on the cyclic trim indicators at calibrated airspeeds below 60 KCAS. Use of extended cyclic trim at low airspeeds will result in high aft rotor blade stresses.

NOTE

Accurate maximum allowable gross weight values for airspeeds 0 to 110 KTAS can be determined by cross referencing the Maximum Gross Weight For Planned Conditions chart (Figure 5-10) with the conditions of pressure altitude and free air temperature (density altitude) as used for Figure 5-8 and 5-9.

Question 28

Maximum Gross Weight Chart for Planned Conditions

Answer 28

The gross weight determined on this chart is the same value that applies to Figure 5-8 at airspeeds at or below 110 KTAS and to Figure 5-9 at airspeeds at and below 49 KTAS.

Question 29

DAFCS Limitations

Answer 29

The airspeed limit when operating on single DAFCS is 100 KCAS or Vne, whichever is slower. The helicopter may be operated with both AFCS off up to 160 KCAS or Vne, whichever is slower, provided both DAFCS are disabled below 100 KCAS.

Question 30

Aerobatics Prohibition

Answer 30

Aerobatics are prohibited with this helicopter. Aerobatics are de􀂿ned as intentional maneuvers beyond ± 30° pitch and/or 60° roll.

Question 31

Bank Limitations

Answer 31

The following bank angle limits apply:

1. With an operative CGI, bank angles are limited by the CGI, but no greater than 60°. When operating with BALT/RALT engaged, limit bank angles to 45° maximum.

2. With an inoperative CGI, use the bank angle limits de􀂿ned by Figure 5-11.

Question 32

Landing Limitations

Answer 32

1. The maximum ground speed for Roll-onlandings is 60 KGS.

2. The maximum nose-up attitude during landings is 20°.

3. The maximum rate of descent at touchdown for gross weights up to 33,000 pounds is 492 ft/min.

4. The maximum rate of descent at touchdown for gross weights from 33,000 to 40,000 pounds is 450 ft/min.

5. The maximum rate of descent at touchdown for gross weights above 40,000 pounds is 360 ft/min.

Question 33

Ground Operation Limitations

Answer 33

To prevent droop stop pounding when all landing gear are in contact with the ground and the THRUST CONT lever is at ground detent, 􀃀ight control movements shall not exceed the following from the neutral position:

Right or left directional pedal - 0.75 inch

Aft cyclic - 2.00 inches

Lateral cyclic - 1.00 inch

THRUST CONT - lever No lower than ground detent

When ground taxiing less than 75 feet from an obstruction on an unimproved/unfamiliar air􀂿eld not designated for CH-47F helicopters, a blade watcher and taxi director shall be positioned as shown in Figure 8-2. If the air􀂿eld is designated for CH-47F helicopters and taxi ways are in accordance with UFC 3-260-01, the above does not apply.

Question 34

Flight Under Instrument Meteorological Conditions (IMC)

NOTE

​WARNING

Answer 34

This helicopter is quali􀂿ed for IMC flight provided the following conditions exist:

NOTE

Should one DAFCS fail during IMC flight, the flight may be continued to destination. Should both DAFCS fail during IMC flight, exit IMC as soon as practical.

1. Both DAFCS are operational.

2. Both Standby Flight Displays (SFD) are operating.

3. Three MFDs (1, 4 and either 2 or 3), two CDUs, two GPPUs, two DCUs, two EGIs, and two ADCs are operational.

WARNING

During ILS approaches outside of localizer limits, the FD cue may continue to command a descent with a MISSED APPR annunciator. In the coupled mode, the aircraft will continue to descend automatically on the glideslope.

4. Coupled ILS approaches at localizer intercept angles of greater than 60° are prohibited.

Question 35

Shock Absorber Vent Valve

Answer 35

The shock absorber vent valve must be open for operation below -18° C. The valve must be closed for operation above -1° C. Dangerous ground and 􀃀ight conditions can result if the valve is in the wrong position. At -18° to -1° C the valve may be opened or closed.

Question 36

Flight in Ice

Answer 36

CAUTION

During flight in icing conditions with the EAPS installed, the bypass doors must remain closed.

Pitot tube and AFCS yaw port heating, and windshield anti-icing systems enable safe flight in light icing conditions. The EAPS is designed to permit safe flight in light icing conditions. Continuous flight in light icing conditions below +5° C is not recommended since blade damage can occur from asymmetric ice shedding. Intentional flight into known icing conditions with rotor blade erosion protection materials installed is prohibited. Icing conditions include “trace,” “light,” “moderate,” and “heavy.”

Question 37

Thunderstorm Operations

Answer 37

To ensure adequate lightning strike protection, the lightning protection cables and straps must be installed and intact on all rotor blades. If any lightning cables or straps are missing or broken, avoid flight in or near thunderstorms, especially in areas of observed or anticipated lightning discharges.

Question 38

Operation With Skis

Answer 38

If skis are installed, the following limits apply:

1. The maximum allowable airspeed is limited to 130 KCAS or Vne, whichever is slower.

2. The maximum allowable rate of descent at touchdown in snow is 480 ft/min at gross weights up to 33,000 pounds, decreasing linearly to 240 ft/min at 46,000 pounds gross weight. For gross weights 46,000 pounds to 50,000 pounds, the rate of descent is 240 ft/min.

3. The maximum taxi speed is 5 KNOTS groundspeed when operating on hard prepared surfaces.

Question 39

Night Operation on Water

NOTE

Answer 39

NOTE

Translational Rate Command (TRC) and Position Hold (PH) must be disarmed for water operations.

Night operation on water is permissible provided:

• Both DAFCS are operational.
• Pilot and copilot radar altimeter is operational.
• A visible horizon is present at the landing site.
• Two ormore highly visible, stationary objects are on the water surface to provide necessary visual cues for landing.

Question 40

Water Operation Time Limit

Answer 40

Operation on water is restricted to 30 minutes total flotation time without draining the helicopter.

Question 41

Water Gross Weight Limitations

Answer 41

Maximum gross weight for water operations is as follows:

• Normal operations - 36,000 pounds.
• Emergency rescue missions - 46,000 pounds.

Question 42

Water Taxiing Limitations

Answer 42

Taxiing will not be conducted in water conditions above Sea State 1 or in wind above 6 knots. Fast taxiing will be conducted in a straight line only and to a maximum speed of 10 KGS when the lower nose enclosure is left in the water.

Question 43

Water Landing Limitations

Answer 43

Water landings can be performed within the limitations presented in Figure 5-13. The touchdown speeds presented do not re􀃀ect indicated airspeed but actual forward velocity at touchdown. Running landings will only be conducted onto calm water. The ramp, lower rescue door, and main cabin door shall be closed during water landing. Water landings are prohibited when fuel in the main tanks is less than 50%.

Question 44

Water Rotor Starting and Shutdown Limitations

Answer 44

Rotor starting or shutdown will not be conducted when water conditions exceed Sea State 1 or wind exceeds 6 knots. Maximum gross weight for starting and shutdown is 28,550 pounds.

Question 45

Air-to-Ground Towing

Answer 45

Air-to-ground towing operations are prohibited.

Question 46

APU Operation

Answer 46

APU operation in 􀃀ight is prohibited except during emergencies.

Question 47

Pitot Tube and AFCS Sideslip Port Anti-Icing Limitation.

Answer 47

The PITOT HEAT switch shall not be on for more than 5 minutes on the ground.

Question 48

Windshield Heat

Answer 48

Windshield heat shall not be used above 24° C.

Question 49

Single Point Refueling

Answer 49

The maximum rate for pressure refueling is 300 gal/min at 55 psi.

Question 50

Extended Range Fuel System II (ERFS II/RSERFS)

CAUTION(S)

Answer 50

The following paragraphs contain important operating limits and restrictions that shall be observed during the operation of the ERFS II/RSERFS. Compliance with these limits will allow the operator to safely perform the assigned missions and derive the maximum utility from the ERFS II/RSERFS.

1. The maximum capacity of one ERFS II tank assembly is 825.5 US gallons when gravity refueled. The usable fuel in one ERFS II tank assembly is 800 US gallons when single point pressure refueled.

The maximum capacity of one RSERFS tank assembly is 516 US gallons when gravity refueled. The usable fuel in one RSERFS tank assembly is 500 US gallons when single point pressure refueled.

CAUTION

Trying to pressure refuel the tanks without connecting the vent lines could over-pressurize the tanks.

2. The maximum internal pressure of the ERFS II/RSERFS tank should not exceed 5 psi.

CAUTION

Conducting suction defueling at pressures greater than -11 psi could damage the internal components of the ERFS II/RSERFS tank assembly.

3. The maximum allowable suction defueling pressure is -11 psi.

Question 51

EGI GPS Limitation

Answer 51

The EGIs are not approved by the FAA for use as a primary source of navigation during Instrument Flight Rules (IFR) conditions. One of the contributing factors is that it is possible for the GPS to receive data from a bad satellite and be used by the EGI for its blended solution (GPS/INU, etc.).