This is an annual topic of conversation on the forums, usually raised by prospective CFIs who will go off and teach it to their students. Although many pilots seem to like to use some in-flight power check, the performance data in the aircraft POH, a little planning before departure, and monitoring of performance and the environment during your approach, in my opinion, supersedes any roll-your-own power check. Maybe this isn’t true when you’ve been out in the real world for 3000 hours and are working at high density altitudes, high elevations, and high gross weights. But for flight training, is this really necessary?

My method, and it’s rationale, are in this post. Basically, determine your performance using published HOGE data, and known/expected conditions. Then, set a limit to what you’ll ask of the aircraft. Monitor power requirements as you terminate the approach, and make a decision about continuing the approach prior to losing ETL.

Other methods

Like everything else on this site, I’m not making any claims as to the validity, safety, efficacy, or correctness of these. As you can see, there are many variations to the power check protocol. Also note that none of the authors differentiate between the R22, 269/300, R44, or any other aircraft. Feel free to add your own.

The most “official” method that I’ve found, from the book Helicopter Pilot’s Handbook of Mountain Flying and Advanced Techniques by Norman Bailey and is also discussed in Principles of Helicopter Flight by Wagtendonk:

1. At a safe height, fly straight and level into the wind at the speed which gives the best rate of climb for the helicopter;
2. Note the power required;
3. Apply maximum power available;
4. The difference between the values is the power margin, and dictates what type of landing, if any, can be carried out…

From the forums

1. 500 ft AGL, 50 KIAS, carb heat set for landing.
2. Note MAP on base.
3. Estimate PA and temp at the Spot, check chart for max. MAP
4. If the difference is 5″ or more – go for it

1. 53kts airspeed, S+L, carb heat off, read MAP.
2. 6″ margin or higher between whatever you are reading and the limitation should be enough to hover OGE
3. 5″ hover IGE
4. 4″ zero speed landing without hover….

Many landings are preceded by a hover, and since power required to hover is greater than than that required for forward flight, it follows that special care is needed for landings at high gross weights in high density altitudes. Keeping the wind on the nose is essential in such circumstances. The method for assessing the power in hand before landing is based on similar principles to that used for the takeoff, except that it is normally done in forward flight and at an altitude slightly above the landing site. It is usually accomplished as follows:

• Fly straight and level at a pre-determined speed (usually minimum-power speed) with landing rotor rpm selected, taking care to avoid air that is subject to up or downdraughts.
• Note the manifold pressure or torque.
• While maintaining the same rotor rpm, briefly apply full power and note the corresponding change in manifold pressure or torque. (Note that it is usually not practical or necessary to maintain the same airspeed at this point.)
• The difference between the two values gives a clear indication of the type of approach and landing that can be safely carried out at the site.
• Any headwind component will obviously be an advantage here, but it should not be relied upon, as it may abate just when you need it most.
• Using the R22 as an example, six inches of excess MAP should enable an approach to be made to an OGE hover, whereas just three inches of excess MAP will usually mean that only a run-on landing will be possible – but this is not recommended. Refer to the Flight Manual for specifics.
• An alternative method is to check the power required to hover OGE adjacent to the landing site, and compare it with the power available. It is essential that this is done with pre-determined escape route in mind over a clear area with plenty of height to spare, as the amount of power required to hover OGE at high density altitudes is extremely large. The helicopter can quickly develop a high rate of descent if there is insufficient power available. Beware of vortex ring state.

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