R22 POH Hover Charts

[Spike]

Performance charts are for planning purposes. They provide one of three answers to a question. The answers are, yes, no and maybe…….. The question is, can the helicopter…..

 

Limitations are simply a yes, no answer….

[ridethisbike]

Performance charts are for planning purposes. They provide one of three answers to a question. The answers are, yes, no and maybe…….. The question is, can the helicopter…..

 

Limitations are simply a yes, no answer….

 

Right. I understand that in the real world, things are never cut and dry, BUT, as a student at the private level, those charts are a yes or no thing for me. Once I get into commercial, the tune will change, most definitely. For now, though, I find it best to be on the safe side.

[iChris]

Can anybody tell me why there is a line on the OGE and IGE hover charts that is marked 12600 DA? What does it mean?

 

 

I'm also curious where the 11,800ft DA limit for IGE hover comes from. As far as I know, there is no such limit listed in the "Limitations" section? The only altitude limitation there is a max. operating altitude of 14,000ft DA (or 9,000ft AGL), so why don't the lines in the IGE chart continue to 14,000ft?

 

The 11,800' thing I have no idea, which is why I didn't comment on it...

 

 

 

The lines on the IGE hover charts all end at a line marked 12,600’ DA (R22) and 11,800’ DA (R44). What does it mean?

 

That’s all part of the certification process. Part 27 holds part of the story on these charts in CFR 27.1587 (a)(2)(ii). The R22/R44 RFM section 5 (Performance – General) tells the rest of the story.

 

Section 5 (pg. 5-1) reads in part as follows:

 

R22 - “Hover controllability has been substantiated in 17 knot wind from any direction up to 10,600 feet density altitude. Refer to IGE hover performance data for allowable gross weight.”

 

R44 -“Hover controllability has been substantiated in 17 knot wind from any direction up to 9,800 feet density altitude. Refer to IGE hover performance data for allowable gross weight.”

 

The approved certification process outlines the maximum allowable extrapolation (from test data) of 2,000 feet for IGE hover controllability. Therefore, the maximum altitude presented in the RFM is not normally more than 2,000 feet above the density altitude experienced at the high altitude test site.

 

If you add 2,000 feet density altitude to the actual test altitudes in section 5, the extrapolation must end at 12,600 feet density altitude for the R22 and 11,800 feet density altitude for the R44.

 

As a side note, if some areas of hover controllability are negated and so specified in the RFM, i.e., calm winds or winds from a favorable wind azimuth, you maybe allowed extrapolation up to 4,000 feet

Edited June 8, 2012 by iChris

[lelebebbel]

Excellent information as usual, thanks Chris.

[Mikemv]

To All,

 

"The only altitude limitation there is a max. operating altitude of 14,000ft DA (or 9,000ft AGL), so why don't the lines in the IGE chart continue to 14,000ft?"

 

I believe that the listed 14K DA max operating altitude is actually the "Service Ceiling" where the helo will no longer climb at 100fpm or more. Most RFMs will have a similar limitation listed. Manufacturers terms may vary in how this is listed.

 

The performance charts are derived from a perceived realistic operational areas and certainly not when ROC is 100fpm or less.

 

Remember that it is: 1. Wind (speed & direction), 2. DA, 3. Gross weight that govern helicopter performance.

 

The above info comes from "Old Fart" memory and may be inaccurate. HELP!

 

Mike

[iChris]

"The only altitude limitation there is a max. operating altitude of 14,000ft DA (or 9,000ft AGL), so why don't the lines in the IGE chart continue to 14,000ft?"

 

I believe that the listed 14K DA max operating altitude is actually the "Service Ceiling" where the helo will no longer climb at 100fpm or more. Most RFMs will have a similar limitation listed. Manufacturers terms may vary in how this is listed.

 

 

You’re correct, the 14,000 feet DA is the only altitude limitation. The hover performance charts allow quick estimation of aircraft performance. It does not establish an operating limitation. However, the NTSB has upheld enforcement actions, in accident cases, were pilots operated grossly and carelessly outside performance ranges.

 

Two altitudes are normally presented in the RFM to define the operating envelope of a rotorcraft, maximum operating altitude and maximum takeoff and landing altitude.

 

Maximum operating altitude is an operating limitation required by FAR 27.1527 and is the maximum altitude to which operation is allowed. This altitude normally constitutes the maximum cruise or en route altitude.

 

This rule requires that the maximum altitude for operation of the rotorcraft must be established as an operating limitation. The rule is intended to establish en route altitude as an operating limit.

 

Maximum takeoff and landing altitude is the hover in-ground-effect (IGE) ceiling for a rotorcraft as described in FAR 27.49. The hover ceiling and any information pertinent to takeoff and landing are presented in the performance information section of the RFM.

 

For rotorcraft certified to FAR 27, a hover ceiling may not be presented above the altitude at which H-V and IGE controllability tests were conducted plus allowable extrapolation, unless that extrapolated altitude is at least 7,000 feet. If the applicant elects to demonstrate these tests to an altitude below 7,000 feet, then that altitude is the maximum takeoff and landing altitude of the rotorcraft. The maximum takeoff and landing altitude may be coincident with, but never above the maximum operating altitude limitation.

 

Using FAA approved methodology; hover performance may be extrapolated and/or interpolated from test data up to a maximum of 4,000 feet. Experience has shown that IGE handling qualities, height-velocity, and engine operating characteristics should not be extrapolated higher than approximately 2,000 feet density altitude from the test altitude.

 

REF: AC 27-1B - Certification of Normal Category Rotorcraft (pg B-9 to pg B-12; pg G-16)

Edited June 8, 2012 by iChris

[ridethisbike]

I was wondering when iChris was going to chime in... haha