5-1. PURPOSE.

This chapter includes all important operating limits and restrictions that must be observed during ground and flight operations.

5-2. GENERAL.

The operating limitations set forth in this chapter are the direct results of design analysis, tests, and operating experiences. Compliance with these limits will allow the pilot to safely perform the assigned missions and to derive maximum utility from the helicopter.

5-3. EXCEEDING OPERATIONAL LIMITS.

Anytime an operational limit is exceeded an appropriate entry shall be made on DA Form 2408-13. Entry shall state what limit or limits were exceeded, range, time beyond limits, and any additional data that would aid maintenance personnel in the inspection that is required.

5-4. MINIMUM CREW REQUIREMENTS.

The minimum crew requirement consists of only the pilot, whose station is at the right side of the aircraft. Additional crewmembers as required will be added at the discretion of the commander, in accordance with pertinent Department of the Army regulations.

5-5. INSTRUMENT MARKINGS.

The operating ranges for both the helicopter and engine are listed below and shown on figure 5-1 and figure 5-2.

a. Operating Limitations and Ranges. Operating limitations and ranges are illustrated by the colored markings which appear on the dial faces of engine, flight, and utility system instruments. Red markings on the dial faces of these instruments indicate the limit above or below which continued operation is likely to cause damage or shorten life. The green markings on instruments indicate the safe or normal range of operation. The yellow markings on instruments 'indicate the range when special attention should be given to the operation covered by the instrument. Operation is permissible in the yellow range, but is time limited. The blue markings on instruments indicate recommended maximum IAS for autorotation. (Green areas will have a single line and yellow areas two yellow lines. This is for identification under night lighting conditions or when using night vision goggles).

b. (OH-58A) Limitation Markings. Limitation markings consist of strips of semi-transparent color tape which adhere to the glass outside of an indicator dial. All round instruments that have range markings on glass face must also have a white slippage mark between glass and frame. All other limitation markings are painted on dial faces under glasses. The maximum and minimum markings are half red and half white as indicated in figure 5-1, with the red portion of the marking farthest from the limitation.

c. (OH-58C) Limitation Markings. The instrument markings containing the saw tooth red line is placed on the dial face with respect to the operating limit as shown in figure 5-2. The saw tooth edge of the red lines cautions the pilot that he is approaching a limit as shown in figure 5-2. A white dot on the face of the instrument indicates the safe or normal range of operation. A chevron (<) indicates above or below operating limits and to go in direction of point.

5-6. TRANSMISSION OIL TEMPERATURE LIMITS.

Warning light on.

5-7. TRANSMISSION OIL PRESSURE LIMITS.

Warning light on.

Refer to figure 5-2 for transmission oil pressure limits.

5-8. WIND LIMITATIONS.

a. The helicopter can be started in a maximum wind velocity of 45 knots and a maximum gust spread of 15 knots.

NOTE

Gust spreads are not normally reported. To obtain spread, compare minimum and maximum wind velocities.

b. Maximum wind for hovering is 35 knots crosswind and 30 knots tailwind.

c. Maximum wind for mooring is 65 knots parallel to the ground in any direction.

5-9. (OH-58A) FIRING LIMITATIONS.

Barrel life is limited to 40,000 rounds when the 15 minute cooling period between 2000 round loads is not observed.

5-10. TOWING LIMITATIONS.

The maximum gross weight for towing the helicopter is 3000 pounds on prepared or unprepared surfaces.

5-11. ENGINE LIMITATIONS.

Refer to figure 5-2. If N2 limit is exceeded, entry on DA Form 2408-13-1 must include duration and torque indication.

5-12. FUEL OPERATION LIMITS.

a. JP-4. No restrictions are imposed when JP-4 fuel is used.

b. JP-5, JP-8, Jet A and Jet A-1. Operation with these fuels are restricted to ambient temperatures of -18C (OF) and above with a T63-A-700 engine, or -32C (-25F) and above with a T63-A-720 engine. If fuel other than JP-4 is used, a deceleration check must be performed prior to first flight of each day. If autorotations are to be performed a deceleration check will be done prior to each flight. Refer to paragraph 8-18.

NOTE

Engine starting difficulties may be encountered if any fuel other than JP-4 is used at ambient temperatures below +5C (41F).

c. Emergency Fuel Aviation Gasoline (MIL-G-5572) without Tricreasyl Phosphate (TCP).

(1) The helicopter shall not be flown when emergency fuel has been used for a total accumulation time of 6 hours. Entry on remarks section of DA Form 2408-13-1 is required for each time emergency fuel is used.

(2) Practice autorotation is prohibited using emergency fuel.

5-13. STARTER LIMITS.

a. Starter Engage Time - If rise in TOT does not occur during the first 20 seconds, starter engage is limited to the following total times:

b. Starter Engage Time - If rise in TOT occurs during the first 20 seconds, starter engage is limited to the following total times:

5-1 4. ENGINE STARTING LIMITATIONS.

During starting if Nl does not reach 58 percent in a total time at 45 seconds (or 60 seconds below 10C FAT), close throttle and press starter switch until TOT is below 200C. If engine fails to start on third attempt, abort start and make an entry on DA Form 2408-13-1. Starter engage time limits in paragraph 5-13a. and b. above do not apply to engine starting limitations should abort start procedures become necessary.

5-15. HEALTH INDICATOR TEST (HIT).

The HIT is the method by which the aviator in day-to-day flying monitors the aircraft engine condition. This is accomplished by the aviator selecting a Nl speed (%) predicted upon the existing FAT. The TOT must then be compared to a predicted value (Baseline TOT) within a certain tolerance. TOT variation from base line values are logged by the aviator. This log is part of the aircraft records and is an aid to maintenance personnel in monitoring performance trends and troubleshooting the engine. When the difference between the recorded TOT and baseline TOT is ±20C or greater, an entry on DA Form 2408-13-1 will be made to notify maintenance. A difference of ±40C or greater is cause for grounding the aircraft

5-16. HOVERING LIMITATIONS.

Refer to paragraph 5-24.

5-17. CENTER OF GRAVITY LIMITATIONS

Maintain the aircraft within the limits in the center of gravity limitation charts in Chapter 6.

5-18. WEIGHT LIMITATIONS.

3200 pounds maximum gross weight.

5-19. AIRSPEED LIMITS.

a. Refer to airspeed operating limits chart (figure 5-3) for forward airspeed limits.

b. Sideward flight limits are 35 knots.

c. Rearward flight limits are 30 knots.

d. Recommend maximum indicated airspeed for autorotation is 100 knots.

e. Maximum indicated air speed with any door removed is 100 knots

5-19.1. MISSILE JETTISONING - AIRSPEED LIMITS.

Jettisoning shall be accomplished from ball-centered flight at the following airspeed and conditions.

a. 110 knots or less in level flight.

b. 80 knots or less in autorotation.

c. Jettisoning of an empty launcher is prohibited.

5-20. COCKPIT AND CABIN DOOR RESTRICTIONS.

a. Helicopter will not be flown without cabin doors unless heavy duty rear electronics compartment soundproof blanket (P/N 206-070-893-7), or its approved equivalent, has been installed. Helicopter will not be flown with only one cockpit door or one cabin door removed.

b. Whenever equipped with missile launcher installed:

(1) An observer must occupy the left seat when the PDU is installed.

(2) No personnel shall be carried in the passenger compartment when the missile launcher is installed.

c. Whenever any OH-58A/C helicopter is operated without its cabin doors:

(1) All soundproof blankets must be in serviceable condition and firmly attached. Pilot must verify.

(2) It the rear cushions (bottom and back) are modified per MWO 55-1520-228-30-30, they may remain installed provided seat belts and shoulder harnesses are installed, property fastened and tightened.

(3) Loose equipment or components must be removed or secured.

d. Doors shall not be opened in flight.

5-21. FLIGHT RESTRICTION WITH FLOAT LANDING GEAR INSTALLED.

5-22. AEROBATIC MANEUVERS.

Aerobatic maneuvers are prohibited. Aerobatic flight is defined to be any intentional maneuver involving an abrupt change in aircraft attitude, an abnormal attitude, pitch angle greater than ±30 degrees or roll angles greater than 60 degrees, or abnormal acceleration not necessary for normal flight.

5-23. CONTROL MOVEMENTS.

CAUTION

For gross weights greater than 3000 lbs and density altitudes greater than sea level, the directional control margin may be significantly reduced while hovering in winds from the right greater then 20 knots or for right sideward flight at speeds greater then 20 knots.

Abrupt control movements, including rapid and repetitive anti-torque pedal reversals are prohibited to avoid excessive stresses in the structure. This restriction in no way limits normal control application.

5-24. HOVERING LIMITATIONS.

Ten percent of total pedal travel, full right to full left, is considered adequate for safe control. The rearward airspeed limit is 30 knots and sideward limit is 35 knots except that control is marginal for certain combinations of relative wind velocity and azimuth angles (measured clockwise from the nose of the helicopter). See Chapter 8 for a description of the marginal wind velocity and azimuth angles.

5-25. FLIGHT RESTRICTIONS AT LOW "G's".

Flight at less than +0.5g is prohibited.

5-26. FLIGHT RESTRICTIONS FOR PRACTICE AUTOROTATION LANDINGS. (Figure 5-4.)

Practice autorotation landings may be accomplished subject to the following limitations.

a. A qualified OH-58A/C IP must be in position to take control of the aircraft.

b. Reported surface winds must not exceed 20 knots.

c. Surface cross wind component must not exceed 10 knots. Wind gust spread must not exceed 10 knots.

d. Touchdown rotor RPM must not be less than 64%.

e. Ground speed at touch down should be approximately 5 knots.

f. Airspeed during glide shall not be less than that established for minimum rate of descent.

CAUTION

In any event, relatively long ground runs with the collective up, or any tendency to float for long distance prior to skid contact should be avoided. If vibrations are encountered after touchdown immediate lowering of the collective is recommended.

g. Upon ground contact, collective pitch must be reduced smoothly to bottom stop without delay while maintaining cyclic pitch near center position. Application of aft cyclic should be avoided.

h. Touchdown autorotations downwind are prohibited.

5-27. FLIGHT RESTRICTION OF TAIL ROTOR CONTROL.

Helicopter will not be flown unless the Primary Directional Anti-Torque System and the Vulnerability Reduction (backup) Directional Anti-Torque system are both operable. This restriction does not apply after compliance with MWO 55-1520-228-50-30.

5-28. FLIGHT RESTRICTION FOR HIGH POWER.

NOTE

In aircraft equipped with IR exhaust stacks, rate of climb in excess of 1 000 ft/min may result in divergent aircraft pitch oscillation which can reach 20 to 30 degree attitudes. This divergence can be alleviated by either increasing airspeed during steady climbs or decreasing rate of climb. Climb rates in excess of 1000 ft/min should be avoided.

5-28.1. SLOPE LANDING/TAKE-OFF LIMITATIONS.

Slope Operations shall be limited to slopes of 8 degrees or less.

Caution

Caution is to be exercised for slopes greater than 5 degrees since rigging, loading, terrain and wind conditions may alter the slope landing capability. See Rollover Characteristics in FM 1-203.

5-29. FLIGHT UNDER INSTRUMENT METEOROLOGICAL CONDITIONS (IMC).

This aircraft is restricted to visual flight conditions. Flight into instrument meteorological conditions will be conducted on an emergency basis only.

5-30. FLIGHT RESTRICTIONS IN FALLING OR BLOWING SNOW.

Flight in falling or blowing snow is prohibited except for those helicopters with the reverse flow inlet fairing installed. Helicopters having the above features may be flown in falling or blowing snow provided reverse flow inlet fairings are installed and the following criteria is met.

a. Visibility reduced by snow must be at least 1/2 mile.

b. Prior to initial takeoff and each subsequent takeoff, inspect the helicopter as follows:

(1) Inspect inlet for possible accumulations of snow, slush, or ice. Accumulations must be removed from the interior of the reverse flow inlet (hand removal is acceptable).

(2) Inspect the engine plenum chamber through the plexiglass windows (a flashlight may be required) on each side of the inlet cowling for snow, slush, or ice, paying particular attention to the firewalls, rear face of the particular separator, bottom corners, and protruding surfaces such as guide vanes, etc.

(3) Visually inspect the plastic particle separator eductor tubes on each side of the engine fairing for obstructions and snow. A thin film of ice about the interior of each tube is acceptable. External ice adjacent to the eductor tubes is acceptable.

5-31. FLIGHT OVER SALT WATER.

CAUTION

Prolonged hovering over salt water which results In spray Ingestion, Indicated by spray on the windshield, should be avoided.

Salt spray ingestion in turbine engines may result in a deterioration in performance as well as a loss in compressor stall margin. When operating within 10 miles of salt water or within 200 miles of volcanic activity appropriate entries should be made on DA Form 2408-13 to alert maintenance.

5-32. FLIGHT IN SAND AND DUST CONDITIONS.

During operations in heavy sand or dusty conditions without the new improved nozzles will result in lower inlet particle separator (IPS) efficiency which in turn severely shortens the engine life.