Part 61 -- Certification: Pilots, Flight Instructors, and Ground Instructors

Until the FAA completes its research into the conditions and aircraft characteristics that lead to main rotor blade/fuselage contact accidents, and corrective type design changes and operating limitations are identified, pilots are strongly urged to become familiar with the following information and comply with these recommended procedures.

Main Rotor Stall: Many factors may contribute to main rotor stall and pilots should be familiar with them. Any flight condition that creates excessive angle of attack on the main rotor blades can produce a stall. Low main rotor RPM, aggressive maneuvering, high collective angle (often the result of high-density altitude, over-pitching [exceeding power available] during climb, or high forward airspeed) and slow response to the tow main rotor RPM warning horn and light may result in main rotor stall. The effect of these conditions can be amplified in turbulence. Main rotor stall can ultimately result in contact between the main rotor and airframe. Additional information on main rotor stall is provided in the Robinson Helicopter Company Safety Notices SN-10, SN-15, SN-20, SN-24, SN-27, and SN-29.

Mast Bumping: Mast bumping may occur with a teetering rotor system when excessive main rotor flapping results from low "G" {load factor below 1.0) or abrupt control input. A tow "G* flight condition can result from an abrupt cyclic pushover in forward flight. High forward airspeed, turbulence, and excessive sideslip can accentuate the adverse effects of these control movements. The excessive flapping results in the main rotor hub assembly striking the main rotor mast with subsequent main rotor system separation from the helicopter.

To avoid these conditions, pilots are strongly urged to follow these recommendations:

1) Maintain cruise airspeeds greater than 60 knots indicated airspeed and less than 0.9 Vne.

2) The possibility of rotor stall is increased at high-density attitudes; therefore, avoid flight at high density altitudes.

3) Use maximum "power-on" RPM at all times during powered flight.

4) Avoid sideslip during flight. Maintain in-trim flight at alt times.

5) Avoid large, rapid forward cyclic inputs in forward flight, and abrupt control inputs in turbulence.

Our Ref: 9/66/12/09

Mr S L Zuckerman

Consultant

Product Integrity Programs

Dear Mr Zuckerman

ROBINSON R22 & R44 HELICOPTERS

Thank you for your e-mails regarding the R22 and R44 helicopters.

The UK Civil Aviation Authority (CAA) has been concerned about the accident rate of small and medium helicopters used for private flying. As a consequence a joint CAA and industry action group was set up to review the number of fatal helicopter accidents with the aim of reducing them. This review was not limited to single engine helicopters nor to the R22 or R44. As a result of the group's work, an education and safety promotion campaign has been launched in the UK, highlighting the hazards of flying small helicopters.

With regards to your comments about the Pilot's Operating handbook for the R22. The situation in the UK is as follows:

The notes on Main Rotor Stall and Mast Bumping that are contained in the 'Normal Procedures' page that you claim are missing from many POH in the UK were issued by Robinson to reflect the text iii FAA AD 95-26-04. This page only covers part of the AD. The AD is mandatory for all UK registered R22 Helicopters and introduces additional mandatory information into the Limitations section of the POH. The AD also includes advisory information for inclusion into the Normal Procedures and Emergency Procedures sections of the POH.

UK operators must have all three parts of the AD incorporated into their POH. The 'Robinson' pages are not identified and are therefore uncontrolled and, in their present form, are not considered by the UK CAA as an acceptable alternative means of compliance with the AD. The pages may be used as being additional to the AD.

The issue of the AD was promulgated in the UK General Aviation Safety Information Leaflet (GASIL) No 2 of 1995..

 In summary, it is not necessary to have the 'Robinson' page in the POH as it only provides information additional to the AD.

The situation with AD 95-26-05 for the R44 is similar.

We will be highlighting the AD and the requirement for the information to be in the POH in our next issue of GASIL

Yours sincerely

Garry Bisshopp