OH-58A/C Limits

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OH-58A/C Limits
2010-04-10 23:45:41
OH 58A C

OH-58A/C System Limits
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  1. Airspeed
    G 0 to 120 knots normals operations

    • R 120 Knots Maximum
    • refer to figure 5-3 for additional information (airspeed limits)

    B 100 recommended maximum for Autorotation
  2. Ammeter
    R This limit mark not applicable
  3. Transmission Oil Pressure
    G 30 to 60 PSI Normal Operation

    R 30 PSI minimum

    R 70 PSI maximum
  4. Rotor Tachometer
    G 93 to 110 percent, Normal Operation

    Y 49% to 58% continuous operation prohibited

    R 93 Percent minimum

    R 110 Percent maximum
  5. Engine Tachometer
    G 98 to 100 Percent, Normal Operation

    R 100 Percent Maximum

    • 15 maximum transient N2 is 110% (Autorotation)
    • Avoid Steady-State conditions between 78-88% N2
  6. Torquemeter
    G 0 to 85 percent Normal Opeartions

    Y 85 to 100 percent 5 minute Operation

    R 100 Percent maximum
  7. Turbine Outlet Temperature Indicator (TOT)

    • 0 C to 810 C Normal
    • Above 810 c to 927 C Maximum 10 seconds
    • R 927 maximum 1 second

    Continuous Operation:

    • 300 C Minimum
    • G 300 C to 738 C Normal Operation
    • Y Above 738 C to 810 C 30 minutes limit
    • R 810 C Maximum. Above 810 C to 843 C during power transient, 6 second Max
  8. Engine Oil Pressue
    R 50 PSI minimum

    Y NOTE: disregard yellow and green instrument markings for engine oil pressure

    • G idle to 78% N1 50-130 PSI
    • Above 78% to 89% N1 90-130 PSI
    • Above 89% N1 115-130 PSI

    R 130 PSI Maximum

    CAUTION: During cold weather start, maximum may go to 150 PSI, but you must remain at engine idle position until normal limits are attained.
  9. Engine Oil Temperature
    G 0 C to 107 C continous operation

    R 107 C Maximum

    NOTE: during cold weather operation the engine may be operated at engine oil temperatures down to -50 C
  10. Fuel Quantity
    Y 0 to 65 low fuel
  11. Gas Producer Tachometer indicator
    R 105 Percent Maximum

    • G 62 to 105 percent Normal Operation
    • Above 105 to 106 percent permissible for 15 seconds
  12. Transmission Oil Temperature limits
    110 C - Warning Light On
  13. Transmission Oil Pressure Limits
    30 +/- PSI minimum - Warning Light On

    NOTE: Light will remain on until 36 PSI is exceeded
  14. Wind limitations
    a. The helicopter can be started in a maximum wind velocity to 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
  15. Towing limitations
    The maximum gross weight for towing the helicopter is 3000 pounds on prepared or unprepared surfaces
  16. 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. Operations with these fuels are restricted to ambient temperatures of -32 C (-25 F) and above. If fuel other than JP-4 is used, a deceleration check must be performed prior to first flight of the day. If autorotations are to be performed, a decleration 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 +5 C (+39 F).

    • 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 accumultaed time of 6 hours. Entry in 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
  17. Engine starting limitations
    During starting if N1 does not reach 58 percent in a total time of 45 seconds (or 60 seconds below 10 C FAT), close throttle and press starter switch until TOT is below 200 C. If engine fails to start on third attempt, abort start and make an entry on DA Form 2408-13-1.
  18. Health Indicator Test (HIT)
    HIT is the method by which the aviator in day-to-day flying monintors aircraft engine condition. This is accomplished by the aviator selecting N1 speed (%) predicted upon the existing FAT. The TOT must then be compared to predicted value (Baseline TOT) within a certain tolerance. TOT variation from baseline values are logged by the aviator. This log is part of aircraft records and is an aid to maintenance personnel in monitoring performance trends and troubleshooting the engine. When the difference between recorded and baseline TOT is +/- 20 C or greater, an entry on DA Form 2408-13-1 will be made to notify maintenance. limits for grounding are +/- 40 C.
  19. Weight Limitations
    Maximum gross weight is 3200 pounds
  20. 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 airspeed with any door removed is 100 knots
  21. 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 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) If 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, properly fastened and tightened.
    • (3) Loose equipment or compnents must be removed or secured

    c. Doors shall not be opened in flight
  22. Flight restriction with Float landing Gear Installed
    a. Airspeed Limit. Float landing great installed - Rearward and sideward airspeed limit is 30 knots. Figure 5-3

    • b. Altitude LImitation
    • (1) maximum operating - 15,000 feet altitude
    • (2) Flight to lower altitude - increase pressure 0.5 PSI per 1000 feet below base altitude, to minimum operating altitude
    • (3) Flight to higher altitude - Limit climbing flight to 8000 feet differential pressure altitude. Above 8000 feet differential pressure altitude, reduce float pressure 0.5 PSI per 1000 feet.
  23. 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.
  24. Control Movements
    CAUTION: For gross weights greater than 3000 lbs and density altitudes greater than seal level, the directional control margin may be significantly reduced while hovering in winds from the right greater than 20 knots or for right sideward flight at speeds greater than 20 knots.

    Abrupt control movements, including rapid and repetitive anit-torque pedal reversals are prohibited to avoid excessive stresses in the structure. This restricion in no way limits normal control application.
  25. Hovering Limitations
    Ten percent of total pedal travel, full right to full left, is considered adaquate for safe control. The rearward airpseed 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 (meansured clockwise from the nose of the helicopter). See chapter 8 for description of the marginal wind velocity and azimuth angles.
  26. Flight restrictions at low "G's"
    Flight at less than +0.5g is prohibited
  27. Flight restrictions for practice autorotation landings
    Practice autorotation landing 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 crosswind 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 touchdown should be approximately 5 knots

    f. Airpseed 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 tendancy 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 cylic pitch near center position. Appliction of aft cyclic should be avoided.

    h. Touchdown autorotations downwind are prohibited
  28. Flight restriction for high power
    NOTE: In aircraft equipped with IR exhaust stacks, rate of climb in excess of 1000 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 100 ft/min should be avoided
  29. Slope landing / Take-Off limitations
    Slope Operations shall be limited to slopes of 8 degrees or less

    CAUTION: Caution is to be exerciesed 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.
  30. 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.
  31. Flight Restrictions in falling or blowing snow
    Flight in falling or blowing snow is prohibited except for those helicopters with reverse flow inlet fairing installed. Helicopters having the above features may be flown in falling or blowing snow provided reverse flow inlet fairing are installed and the following criteria is met.

    a. Visibility reduced by now must be atleast 1/2 mile.

    b. Prior to inital take off and each subsequent take off, inspect the engine as specified in CH 8, section V, paragraph 8-34
  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.
  33. Flight in Rain, Snow and Icing conditions
    If flown in rain, snow or icing conditions, appropriate entries should be made on DA Form 2408-13-1 to alert maintenance
  34. Turbulence limitations
    a. Intentional flight into severe or extreme turbulence is prohibited

    b. Intentional flight into moderate turbulence is not reommended when report or forecast is based on aircraft above 12,500 pounds gross weight

    c. Intenional flight into thunderstorms is prohibited