Performance Planning Flashcards
What is the Engine Torque Factor (ETF)? Will it ever be above 1.0? What is the range?
ETF is the ration of individual engine torque available compared to a specification engine at a reference temperature of 35 degrees Celsius. It will never be above 1.0. The range is from 0.85 to 1.0.
What is the Aircraft Torque Factor (ATF)? What is the range?
ATF is the average of both of the ETFs for the aircraft. It can range from 0.90 to 1.0.
What is the Torque Ratio (TR)?
The TR provides an accurate indication of available power by incorporating ambient temperature effects on engine performance. For temperatures below 35 degrees Celsius, the denser air makes the engines more efficient (to a point…about -5 degrees Celsius due to NG limiting).
Can the ATF Torque Ratio by computed by averaging the ETF Torque Ratios?
No, it must be computed separately using the chart.
What does Max Torque Available represent?
It reflects the maximum torque the engines can produce without exceeding TGT limiting (dual engine - 10 minute limit, single engine - 2.5 minute limit), NG limiting, or fuel flow limiting.
When is Max Torque Available (MTA) considered a structural limitation? Environmental?
If MTA is above the dual-engine or single engine torque limits, the aircraft is said to be structurally limited. The engines are capable of producing the power, but the components of the XMSN are incapable of sustaining the torque loads continually without damage.
If MTA is below the dual-engine or single-engine torque limits, it is said to be environmentally limited. Due to the environmental conditions, the engines are incapable of producing specification power and XMSN torque limits will not be reached.
What type of limiting can limit MTA when it is a structural limitation (dual-engine)?
TGT or NG limiting can limit MTA.
In what conditions would TGT limiting restrict MTA? NG limiting?
TGT would restrict MTA in hotter conditions, and NG limiting would restrict MTA in colder conditions.
If you have two different ETFs, will you actually see the MTA dual-engine number in the cockpit? What will you see?
No, each engine will rise to its single engine MTA.
What will happen if you demand more power than MTA?
The rotor will droop.
How is MTA affected by bleed air (anti-ice and heater)?
MTA is reduced by 20% with Engine Anti-Ice on, and 5% with the Cockpit/Gunner Heater on (7.5% with Cockpit/Gunner Heater and auxiliary bleed-air cabin heater on).
If you are cruising at 42% TQ and you have 100% MTA, and you turn on anti-ice, will you see a change in torque?
No, MTA is reduced off the top. MTA will be reduced to 80%, but since you are only operating at 42% you will not notice a change in torque.
When is MAX ALLOWABLE GWT IGE/OGE a structural limit? Environmental?
If MAX ALLOWABLE GWT IGE/OGE is equal to the max gross weight of the A/C (22,000 lbs), then the aircraft is structurally limited. The engines may be capable of lifting more weight, but the airframe is not.
If MAX ALLOWABLE GWT IGE/OGE is less than the max gross weight of the A/C (22,000 lbs) then the aircraft is environmentally limited. Although the airframe is capable of lifting the weight, the engines cannot lift that weight based on the environmental conditions.
If you are hovering at your GO/NO GO TQ IGE and bring the aircraft up to an OGE hover, what torque value will you see?
MTA
If actual hover TQ does not match PREDICTED HOVER TQ, what could be the cause?
1) A/C weight is not as predicted.
2) Environmental conditions may have changed.
3) There could be a crosswind or strong winds. Hover values are based on zero wind conditions.
4) Hovering over other than level and smooth surfaces can affect hover TQ.
5) There was an error in deriving the value from the chart (or incorrectly entered into IPAC.
