US authorities worry about accepting Robinson Helicopter. Australian cowboys show that training is the key to safe use.
Ramon Lopez/WASHINGTON DC
The US Federal Aviation Administration's (FAA) latest move to beef up flight-training requirements for the Robinson Helicopter R22 and R44 follows a year of record sales of the types. The paradox is only the latest twist in a saga marked by bitterness between the Torrance, California piston-helicopter manufacturer and the US National Transportation Safety Board (NTSB).
The new action stops short of accepting recommendations from the NTSB to ground the helicopters. Further action may still follow from the FAA investigation into the types, but FAA officials say the new pilot and certificated flight instructor (CFI) training rules, and the airworthiness directive already issued are prudent measures pending completion of research.
Robinson Helicopter owner and founder, Frank Robinson, largely backs the FAA's actions, which follow a series of unexplained accidents. He says, though, that the new rules restricting flight operations should be applied only to student-pilots. He charges that the Safety Board's probe of his aircraft is "vindictive and politically-motivated" and is being conducted by officials who are not qualified to evaluate design safety.
Robinson says the negative publicity has not affected sales to date, but he fears that it could in future. Two US schools are dropping the Robinson as a result of the controversy.
The NTSB recommended a year ago that the FAA conduct an R44 special certification review (SCR) after ruling that the probable cause of a fatal R44 crash in 1993 was fatigue failure of the cyclic control stick assembly. It also raised questions about FAA oversight of the R44 design certification process.
In July, the FAA said the R44 passed the SCR. Although Robinson Helicopter redesigned the R44's cyclic control system to increase strength margins, the FAA ruled that the original design met its requirements. At the same time, however, the FAA issued a special "airworthiness alert" recommending that R22 and R44 pilots limit forward flight airspeed to the minimum possible, and face into the wind when hovering out of ground-effect. They were also urged to avoid turbulence and maintain balanced flight.
The FAA insists that the R22 and R44 comply with certification criteria for light civil helicopters incorporating "teetering" rotor designs, but the NTSB believes that the unique design of the R22 and R44 rotor system may result in flight characteristics that are not adequately addressed by the existing certification standards. It says that some R22 and R44 in-flight break-ups are believed to have occurred while the rotorcraft were being operated at speeds well within the aircraft's defined operating envelope.
A total of six R22s and R44s were destroyed in fatal accidents in 1994 involving in-flight contact between the main rotor and the fuselage. Since 1979, there have been 26 R22 and two R44 fatal accidents. The FAA says pilot experience was a factor in 24 of the accidents and that most of them were caused by either low RPM rotor-stall or mast-bumping. The NTSB says: "Of special concern...are the effects that turbulence may have on the main-rotor control-system and ergonomic factors relative to the interaction between the pilots through the unique teetering cyclic-control systems in the R44 and R22 helicopters."
Accidents have occurred with no apparent warning, indicating that "undesirable aerodynamic characteristics of R44 and R22 main rotor blades can result in one or both blades diverging from their normal plane of rotation during normal operation in the approved flight envelope", it continues.
The FAA in January issued an airworthiness directive (AD) requiring implementation of the measures recommended in the previous alert. It bars flights if surface winds exceed 25kt (45km/h), gusts exceed 15kt or if wind shear or turbulence is forecast. The AD limits forward airspeed to the minimum possible, with 80kt the maximum allowable in turbulence. The FAA's Flight Standards Branch then issued new requirements for R22 and R44 pilot training.
Frank Robinson says he cannot find "an inherent design problem" in either the R22 or the R44. He blames inadequate training for the spate of fatal rotor-strike accidents and says that the wind and turbulence operating restrictions in the AD should apply only to student-pilots. "All pilots have different skills...You can't hold a 4,000-5,000h pilot to the same limit as a student," he adds.
R22 and R44 operators back Robinson on this issue. Steve Schubert, who heads Advanced Helicopter Concepts, has operated R22s in flight training for seven years' logging over 10,000 flight hours. In a letter to FAA administrator David Hinson, Schubert notes that his flying school has been accident and incident-free. "This is not a random act of fate, but due to proper training by conscientious and safety-minded professional instructors. Any restrictions...preclude even highly accomplished pilots from exercising their proven abilities," says Schubert. He says that the AD "...poses undue economical hardship on our company, likely to the point where jobs will be lost."
Robinson believes that the minimum number of helicopter flight hours needed to qualify as an instructor, should be 250h. It is now 50h. CFIs must be qualified to teach emergency procedures, including recovery from low RPM rotor stall and low-g mast bumping. "Mast bumping" on teetering rotors describes the impact of the mast or shaft on which the rotor is mounted against the rotor-hub. It occurs when the rotor disc tilts excessively and, although not uncommon, can be dangerous if it is violent and particularly if it leads to the blades flexing downwards enough to contact the airframe. Robinson adds. He is also pushing for the mandatory retrofit of a collective-mounted RPM-governor on the R22. Based on the unit used in the R44, it would help combat the potential for low RPM rotor stall by reducing pilot workload.
Robinson says that the NTSB is being vindictive towards his company, a charge the NTSB denies. "I think the FAA has been too weak politically. They have been, too easily intimated by the NTSB. I don't think the FAA should allow the NTSB to dictate the design of aircraft since the NTSB does not have any expertise in this area," he says.
He says that the NTSB action was triggered by the 27 December 1994 fatal accident involving an R22 which crashed near Zurich. The pilot, with 90h total time in helicopters (20 hours in the R22), flew into winds gusting to 50kt on the downward side of a hill. He says there was no evidence of mechanical failure or malfunction and low RPM rotor stall is suspected.
In a fatal UK R22 accident on 8 June 1994, however, the issue of pilot inexperience is not so clear. Examination of the wreckage revealed, that the tail-boom was struck by the main rotor-blades. Pilot Harry Knapp, the owner and proprietor of the Bizzi-B Helicopters flight training school, had accumulated 8,400 helicopter flight hours, of which 5,200 hours were in the R22. His student, however, had only 22h on the R22 together with 4,000 airline hours.
Despite recent robust sales, this is all casting a shadow over Robinson's future. Already two major US flight schools are to replace their R22s with Schweizer's new Model 300CB training helicopter - a model which, Schweizer freely concedes, is partly intended to capitalise on the Robinson situation. Helicopter Adventures operates 17 R22s, most of which will be replaced by 300CBs. President Patrick Carr says the NTSB's call to ground the R22 was the "final straw".
Says Robinson: "The NTSB has made many unsubstantiated accusations without basis and in the process has caused a great deal of damage to our reputation and our business. My concern is not just with Robinson Helicopter. It is also with the hundreds of small businesses, operators and flight schools using our helicopters. These operational limitations could force them out of business. That is not right."
Source: Flight International
