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Performance Planning

Performance Planning. PPC Requirements. AR 95-1, para 5-2a tells us that the aviator will evaluate: Aircraft performance Departure, enroute, and approach data Notices to Airmen (NOTAM) DA Form 5701-R may be used as an aid to organize performance planning data required for the mission.

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Performance Planning

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  1. Performance Planning

  2. PPC Requirements • AR 95-1, para 5-2a tells us that the aviator will evaluate: • Aircraft performance • Departure, enroute, and approach data • Notices to Airmen (NOTAM) • DA Form 5701-R may be used as an aid to organize performance planning data required for the mission

  3. PPC Requirements • This form will be used for: • RL progression training • Annual ATP evaluations • When required during other training and evaluations • For evaluation flights, the evaluator will determine the blocks that will be filled out • Be safe and do it all

  4. CURRENT PA = 2500 ft MSL FAT = 25 deg C GWT = 15000 lbs ETF #1 = 1.0 ETF #2 = .98 MAXIMUM PA = 3000 ft MSL FAT = 30 deg C CRUISE PA = 6000 ft MSL FAT = 25 deg C PLANNING CONDITIONS

  5. Engine Torque Factor • ETF • The comparison of an individual engines torque available to a specification engines (1.0 ETF) torque available at a reference temperature of 35 deg C • The ETF must be between .85 to 1.0 • The ETF indicates degradation of performance based on engine usage

  6. Aircraft Torque Factor • ATF • ATF is the average of the two ETF’s. It indicates the aircraft’s total performance capability based on the condition of the two engines. • ATF is also based on 35 deg C and is allowed to range from .90 to 1.0 • If ATF is outside this range do not fly the aircraft

  7. 2500/3000 25/30 15000 .99 1.0 .98 6000 25

  8. Torque Ratio • TR • Torque factor chart indicates improved engine and aircraft performance as temperature decreases below +35 deg C • Torque ratio will be written to three decimal places • Three instances when chart is not needed: • If FAT is +35 degrees or above • If FAT is -15 or below • If ETF is 1.0

  9. Chart Info Torque Factor 100% RPM R Page 7A-7 .982

  10. Chart Info Torque Factor 100% RPM R Page 7A-7 .984

  11. 2500/3000 25/30 15000 .99 1.0 .98 .991 1.0 .982 6000 25 .992 1.0 .984

  12. Max Torque Available • This torque value represents the maximum specification torque available at zero airspeed and 100% RPM R for the operational range of PA and FAT • This value may or may not be continuous due to Chapter 5 limitations

  13. Max Torque Available • The actual MTA figure should be annotated on the PPC, regardless of whether it is above the continuous torque limits • Conditions may arise when the pilot may need transient power demands • The pilot is responsible for ensuring that Chapter 5 transient limits are applied when using this value, if applicable

  14. Max Torque Available • Based on flight test data, the MTA chart reflects the maximum torque the engines can produce without exceeding the maximum of any of your three 30 minute engine operating limits: • TGT = 851 deg C • Ng = 102% • Engine Oil Temperature = 150 deg C

  15. Max Torque Available • MTA is limited by the HMU through Ng limiting • A TGT limiter circuit within the DEC causes the HMU to limit fuel to the Ng engine section when TGT reaches 866 +/- 6 deg C (dual engine) and 891 +/- 5 deg C (single engine)

  16. Max Torque Available • TGT limiting is what will most commonly limit MTA for the PA and FAT combinations that most aviators operate in • The HMU also limits fuel to the Ng section during high ambient temperature conditions

  17. Max Torque Available • At high ambient temperatures, the air becomes less dense, causing the Ng turbine section to operate at higher speeds in order to deliver the same volume of air output to the power turbine wheels (Np) • Fuel flow is limited to prevent excessive operating speeds that could damage the Ng turbine wheels

  18. Max Torque Available • The HMU also limits fuel flow to the Ng section during very cold conditions • Mach speeds decrease as temperature decreases • This limiting is to prevent compressible air flow (mach speeds) from occurring within the compressor inlet section

  19. Max Torque Available • If MTA is more than 100% dual engine (above 80 KIAS), 120% dual engine (80 KIAS or less), or 135% single engine, then the aircraft is structurally limited • The engines are capable of producing the power, but components in the transmission (main module for DE torque and input modules for SE torque) are incapable of sustaining these torque loads continuously without damage

  20. Max Torque Available • In a structurally limited aircraft, attempting to operate continuously above the allowable torque value in Chapter 5 will result in structural damage to the transmission • Maximum torque for a structurally limited aircraft is limited to a 10 second time limitation

  21. Max Torque Available • If MTA is below 100% dual engine (above 80 KIAS), 120% dual engine (80 KIAS or less), or 135% single engine, then the aircraft is environmentally limited • Due to environmental conditions the engines are incapable of producing maximum rated power and transmission torque limits will not be reached

  22. Max Torque Available • In an environmentally limited aircraft, attempting to demand more torque than MTA, will result in rotor bleed-off • Depending on how far the collective is increased beyond this point, will determine how far the rotor will droop • The larger the excursion, the greater the reduction in rotor • The bigger the splat mark

  23. Max Torque Available • It is important to understand what the pilot will observe on the torque gauges when maximum power is demanded • One scenario would be an aircraft with identical ETF’s, resulting in identical MTA values for both dual and single engine operations

  24. Max Torque Available • After doing our planning we find out that out Dual Engine MTA is 114% • When MTA is demanded the pilot would observe 114% torque on both the #1 and #2 engine torque gauges • The respective TGT for each engine would be at the dual engine limiting value (866 +/- 6) • TGT limiting would prevent the pilot from receiving more torque

  25. Max Torque Available • A more common scenario would be having different ETF’s (1.0 and .948) resulting in a different MTA for each engine • In this situation when MTA is demanded, the pilot would not see 114% on the torque gauges, as this is only an averaged number between the two engines • As the pilot demanded power, torque on both engines would rise evenly to 108%

  26. Max Torque Available • At this time the #2 engine would reach it’s TGT limiter and would remain at 108% torque • If the pilot continues to demand more power, the stronger 1.0 engine would produce up to 114% before reaching it’s TGT limiter

  27. Max Torque Available • The pilot would observe 114% and 108% respectively, with TGT on both engines at the dual engine limiter • Attempting to demand more power in this case would result in rotor bleed-off • A torque split will be induced by the pilot when power demanded exceeds that of the weakest engine • This is considered normal

  28. Max Torque Available • With bleed-air extracted, adjust MTA as follows: • Eng. Anti-Ice On - Subtract 18% from MTA • Heater On - Subtract 4% from MTA • Both On - Subtract 22% from MTA • This will hold true for SE MTA except the values are half of that stated

  29. Max Torque Available • These values are different for different helicopter models • See the -10 for the values for the UH-60A • Also see the -10 if HIRSS is installed and baffles removed • This is not a normal configuration

  30. Chart Info Max TQ Avail 10 Min Limit Bleed Air Off 100% RPM R Zero Airspeed Page 7A-10 112%

  31. Chart Info Max TQ Avail 30 Min Limit Bleed Air Off 100% RPM R Zero Airspeed Page 7A-11 95%

  32. 25/30 2500/3000 15000 .99 1.0 .98 .991 1.0 .982 111 112 110 112 X .982 = 110 Spec Torque - 112% Spec Torque - 95% 112 X .991 = 111 95 X .984 = 93 95 X .992 = 94 1/2 MTA = 46% 6000 25 .992 1.0 .984 94 95 93

  33. Max Allowable GWT OGE/IGE • This is the most weight the aircraft is able or allowed to pick up to a 10’ hover height for IGE operations or to an OGE altitude (70’ for UH60) for OGE operation • This weight is limited by either engine capability or aircraft structural design

  34. Max Allowable GWT OGE/IGE • The Max GWT for UH60A without provisions for Engine Output Shaft STUD BALANCE MWO or without the wedge mounted pitot static probes is 20,250 lbs • The Max GWT for UH60L or UH60A with the MWO provisions and wedge mounted pitot static probes is 22,000 lbs

  35. Max Allowable GWT OGE/IGE • If the Max GWT IGE or OGE is 20,250/22,000 lbs (as applicable), then your aircraft is structurally limited • Although the engines may be capable of lifting more weight, the airframe is not • When the Max GWT value is 20,250/22,000 lbs, attempting to operate at a weight above that value will result in exceeding a structural design limitation and airframe damage is likely

  36. Max Allowable GWT OGE/IGE • If the Max GWT IGE or OGE is less than 20,250/22,000 lbs (as applicable), then your aircraft is environmentally limited • Although the airframe is capable of lifting up to the Chapter 5 limit, the engines cannot provide enough power to lift that weight for the given environmental conditions

  37. Max Allowable GWT OGE/IGE • When the Max GWT value is less than 20,250/22,000 lbs, attempting to operate at a weight above that value will result in rotor droop (environmental limitation), but no airframe damage should result • Unless you crash from low rotor RPM!

  38. Chart Info Hover Clean Config. 100% RPM R Zero Wind Page 7A-15 21,250 lbs

  39. 2500/3000 25/30 25/30 15000 .99 1.0 .98 .991 1.0 .982 111 112 110 21250/22000 6000 25 .992 1.0 .984 94 95 93

  40. GO/NO GO Torque OGE/IGE • This value is essentially a weight check • At a 10’ hover height, this is the torque that will determine if you are at or below your maximum weight that the engines are capable of lifting to an IGE or OGE altitude • Bottom line…GNG is the hover torque for Max Allowable GWT for the day

  41. GO/NO GO Torque OGE/IGE • If your Max GWT OGE is at the Chapter 5 maximum (ie. 20,250/22000), then only one GNG value will be needed and this will represent both IGE and OGE capability • If you can lift maximum weight to OGE altitudes, then you can obviously do it at IGE altitudes

  42. GO/NO GO Torque OGE/IGE • In this scenario, if the torque required to maintain a stationary hover is at or below the GNG IGE/OGE value, the pilot has confirmed aircraft weight to be at or below Max GWT and any maneuver requiring OGE power or less may be attempted

  43. GO/NO GO Torque OGE/IGE • If the torque required to maintain a stationary hover is above the GNG IGE/OGE, you cannot operate in compliance with the -10 because you are exceeding the aircraft’s maximum structural gross weight • This requires an entry to made to DA Form 2408-13 • The helicopter shall not be flown until corrective action is taken

  44. GO/NO GO Torque OGE/IGE • If your Max GWT is less than the Chapter 5 maximum (20,250/22,000), then a GNG value is required for both IGE and OGE • If the torque required to maintain a stationary hover exceeds the GNG OGE, but does not exceed the GNG torque IGE, then only IGE maneuvers may be attempted

  45. GO/NO GO Torque OGE/IGE • Maneuvers requiring OGE power are: • Perform fast rope insertion • Perform rappelling procedures • Perform rescue-hoist operations • Perform STABO operations • Perform external load operations • Basically, if it hangs under the aircraft don’t do it

  46. GO/NO GO Torque OGE/IGE • Theoretically, if the torque required to hover exceeds the GNG OGE, you should not be able to exceed the GNG IGE for and environmentally limited aircraft since your MTA will equal your GNG IGE and rotor bleed off will develop when engines hit the TGT limiter at 866 +/- 6

  47. GO/NO GO Torque OGE/IGE • Remember, all hover checks are done at an altitude of 10’ • If you are performing external load operations plan a GNG value that will place the load at 10’ AGL (usually 30’ or 40’)

  48. GO/NO GO Torque OGE/IGE • GNG is computed using maximum forecast conditions • When the actual temperature is less than maximum, the torque required to hover at a given GWT is less • To ensure that OGE capability exists and/or structural limitations are not exceeded, reduce GNG by 1% for each 10C that actual temperature is less than maximum forecast

  49. GO/NO GO Torque OGE/IGE • The colder temperatures would allow the same 20,250/22,000 pound aircraft to hover at these weights with less torque • Therefore operating at the higher (original) GNG torque value would mean you are actually hovering an aircraft weighing more than the Chapter 5 limits allowed

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