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3 Answers

Operation of Robinson Helicopters

Asked by: 3710 views Aircraft Systems, Helicopter

I have several (many) questions about Robinson R22/44s. Many NTSB "probable causes" state "loss of engine power for undetermined reasons" and when I say "many" to me it’s way too many.  I've got some ideas what it might be. Also dynamic rollover, what's the problem? Smallest helo I've flown was the 269/300. I know there’s a LOT of Robinsons out there and they are 70% of the civil training fleet but I just want to try to understand the aircraft a little more.

1- A quick explanation of the throttle “governor” please.

2- Stupid question but I gotta ask - There is a mixture control right? Do pilots ever lean this out in flight?

3- Is it overly difficult to maintain an appropriate hover altitude?

4- During autorotations it appears that touchdown and/or power recovery are ahh… “problematic”. Any insights?

(I am a ATP-helo,CommASMEL-I, CFII Helo, AGI 8500+)

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3 Answers

  1. Kris Kortokrax on Sep 04, 2012

    Early on, there were some engine failures due to carburetor icing. Currently, the TBO on the Lycoming engine in the R22 and R44 is 2200 hours. No issues with the engines. What are your “ideas what it might be”?

    1. The governor maintains RPM by adjusting the throttle. You can feel it move with your left hand. Not large movements, but perceptible. When I learned there was no governor on the ship, just like the 269/300.

    2.. I would only lean if necessary for best power at high density altitude. I would use it the same way I would use the mixture control in the 269/300.

    3. It is no more difficult to maintain an appropriate hover altitude than a 269/300. In fact, due to the design of the tail rotor, hovering is easier in higher wind conditions than a 269/300.

    4. Having done and taught both power recovery and touchdown autos in R22, R44 and 269/300 ships, there are no problems due to design. In fact, R44 hass a high inertia rotor and performs autos very similar to a Bell 206. Although the R22 is a low inertia system, the 269/300 ships are low inertia also and the technique is almost identical.

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  2. David A Hatcher on Sep 05, 2012

    Thanks Kris for your info!
    My “idea” is that pilots are leaning the mixture to save gas, fly along into different conditions, forget to enrich and it gets quiet. Obviously without enough time, altitude or hands to get it restarted. Too many investigations end up with the engine on a test stand, or even left in the wreck are started and run to standards. I am a staunch defender of the pilot but I have to start wondering what the common denominator is.
    As for the appropriate hover height, if you’re hovering around you can’t get dynamic rollover if you don’t hit the ground. You can maintain an appropriate hover height if engine and rotor RPM are maintained, hence my question about the governor.
    Doing touchdown autos (or any run-on landing) in the grass/dirt reduces wear on the skids (which I am sure is the primary reason) but it exposes the landing to hitting a “clump of dirt”, unseen ruts, gopher holes and whatever that’s gonna’ flip it over.
    I “assume” the touchdown autos are “run ons”. How “fast” and “far” is considered acceptable?
    (Oh, I’m no big fan of the investigative process. “Big” accidents get the resources; little ones are done by pilot statements and phone calls.)

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  3. Kris Kortokrax on Sep 13, 2012

    I wanted to answer in this thread rather than in the new thread.

    I’m not personally aware of any accidents caused due to leaning. I wouldn’t think that Robinson pilots would lean any more that Schweizer, Brantley, Enstrom or Bell 47 pilots would.

    Regarding hover height, the Robinson R22 was initially certified with a 150 HP engine. It was subsequently increased to 160 HP and then (currently) 180 HP. All versions are derated to 131 HP with a 5 minute limitation and 127 HP max continuous. There are only a handful of the 150 HP ships out there. The margin provided by derating gives ample power reserve to maintain an adequate hover height provided the helicopter is operated in accordance with the HIGE, HOGE charts (as would apply to any of the other helicopters).

    As far as TD autos go, I have always avoided soft surfaces in favor of hard surfaces for TD autos, hover autos and running landings. I figure that skid shoes are cheaper to replace than helicopters. I’ve seen some run-ons in a 206 that went as long as R-22 run-ons. When I was teaching touchdowns regularly in the R-22, I could accomplish them with a run-on no more than the length of the skids.

    As far as what is acceptable, I guess it depends on the skill level of the pilot (for practice autos). For a real life engine failure, if I can get it stopped in the available space, I’d say that’s acceptable.

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