Power Required exceeds Power Available LT Robie NATOPS Officer

Lake Tahoe MH-60R https://www.youtube.com/watch?v=fjUBnlV4nNE If embedded video fails, use link.

Indications Uncommanded descent with torque at maximum available Rotor droop Loss of tail rotor authority Right yaw

When Will it Occur? NOT under normal conditions for a TH-57 Hit torque limits first

When Will it Occur? Engine malfunction Engine limited aircraft Engine Underspeed Compressor Stall FCU Failure (possible, but not always) Engine limited aircraft Hit Ng or TOT limits or Nr droop

Aggravating Factors High G loading High GW High DA Rapid maneuvering High AOB level turns High GW High DA Rapid maneuvering Quick stop Spool up time from lower power to higher power settings Power off wave off Loss of wind effect Descending below a tree line Change of wind direction Loss of ground effect Transition to forward flight from a pinnacle

How to Avoid Pr > Pa Preflight planning to determine expected aircraft performance Plan for ALL phases of flight Heaviest load based on fuel for external load ops Avoid excessive maneuvering, particularly during high DA, hot temperatures, high GW, or marginal power situations Avoid high descent rates Requires large power inputs to arrest rate of descent Keep rotor head loaded Avoid downwind take offs/landings Maintain SA of wind speed/direction, especially during low altitude/low airspeed maneuvers

EP/Effect on Power *1. Collective – Lower as required to maintain a minimum of 90% Nr *2. Twist grip – full open *3. Angle of bank – level the wings *4. Airspeed – adjust to 50 KIAS *5. Jettison – as required If impact is imminent: *6. Level skids to conform to terrain *7. Cushion the landing Decreases Pr Increase Pa Decrease Pr

Power Available Check Conducted when any question about engine integrity “check power available with Nr in limits” Is level flight possible? Raise the collective until the VSI is zero or Nr decays to 90% Adjust airspeed to minimum Pr (~50 kts) as required

Pa Not Sufficient VSI is below zero with Nr 90% and min Pr airspeed Need to autorotate May use what power is available to set up for auto DO NOT BRING TWIST GRIP TO IDLE

Pa Sufficient for Level Flight Able to continue flight Land as soon as possible Determine how much power is available Raise the collective until an operating limit is reached (Ng, TOT, Torque, or Nr < 90%) Allows you to figure out what kind of landing is possible and what is a suitable sight for landing If Pa is below HIGE torque, you will not be able to hover for a vertical landing Sliding landings require least amount of power