Tuesday, March 10, 2015

Reflecting on Loss of Power...

 Losing an engine at that point would result in a very rapid decrease in rotor rpm, and a rapid descent to who-knows-what kind of forced landing area. It would be a lot different than pushing the collective down from level slow-cruise at one thousand feet above the threshold of a big beautiful runway. An excerpt from a post on ready-thinking

Over the last few days, I have been doing some hard thinking about what it will mean to lose power from the single engine in the helicopter I fly. Notwithstanding the high reliability and statistically insignificant risk of failure, engines DO fail and when we only have one, it puts us in a bad situation. I have taken to slightly longer hover checks (to let it quit if it wants to while I am near the ground), and climb-outs at max-continuous power and best-climb speed. Altitude and speed are good when the whining stops.

I spoke with Alex Myers, a young pilot-friend about the failure he experienced in a 333 trainer in Saudi Arabia. He noticed a change in engine sound, took the controls, and said, "now what did you do?" to his student. The student didn't do it - a nut on a pressure line came loose. Alex says "everything slows down and time stretches" as he is doing his first-ever real-live no-crap auto to the surface. He had just cleared a built up area and was over flat open terrain. They were lucky. 

Not everyone is so lucky.

Fellow pilot Juan Terraza told me about his two engine failures. In both cases the problem was the same thing, a nut securing a pressure line vibrates loose, a pressure signal is lost, and the engine spools down. Juan said both problems occurred after making a power adjustment, and advised against moving the collective during climb-out until at a safe altitude for autorotation. So after my hover checks are complete, I make one smooth increase in power to the line and leave the collective still until level off. 

Bad fuel will ruin our day as well...

I continue to consider and announce forced-landing areas, for both arrivals and departures. But I know there will be some situations where a forced landing will be difficult if not deadly. It might be good to start looking at rooftop helipads on hospitals as higher-risk propositions, with some additional forethought on escape paths and forced landing areas. It might even be worth considering to begin an approach to a point in space adjacent to a rooftop pad, sliding over the pad as the approach terminates. If the engine burps, farts, or coughs - down-collective to maintain rotor rpm and fly clear...

I find myself reflecting on the amount of time I spend in the avoid-area of the height-velocity chart - that is the combination of altitude (low) and airspeed (slow) from which an autorotation will not end well. A wire strike is more likely than an engine failure, but there are some areas where a wire strike is unlikely - like on approach to a rooftop helipad. If we know that we are into the wind, and won't hit wires, perhaps a super-slow approach (200 feet per minute rate-of-descent) isn't the best way...

(One cannot land a single engine-helicopter on a rooftop hospital-helipad in the city of Boston. Recent events perhaps bear out the logic of this restriction).

When you read about someone perishing - someone of a similar age and with lots of experience - by all accounts a good and safe pilot - it brings on the hard thinking...

May it not happen to you.

Or me.

Please add your thoughts on this in a comment...

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