To: Try Cyclic
I’m going to put the shoe on the other foot, and ask you to explain in non engineering terms, exactly how this delta hinge effect causes the disc to tilt forward when the cyclic stic is moved in a forward direction, and not to the left, as I indicated that it would. I want you to tell me in your own words and not those of the instructors at Robinson. The same goes for You Will See who in fact is an instructor on Robinson Helicopters.
You made a point saying that dissymetry of lift is greatest when the blades are disposed over the lateral axis of the helicopter. If this were true, the helicopter would roll to the left and quite fast I might add. You are totally wrong. The basic aerodynamics of a helicopter dictate that there is no dissymetry of lift. The advancing blade is at its’ lowest pitch when the blades are in the lateral position and the retreating blade is at its’ highest pitch. The decreased pitch in the advancing blade decreases the lift on that blade and the increased pitch on the retreating blade increases the lift on that blade. In effect, the lift generated on each blade is the same. In the process of this pitch change the disc is tilted providing forward thrust making the helicopter fly forward.
The only time there is a dissymetery of lift is when you start to approach retreating blade stall. In this case the dissymetry causes an imbalance of forces causing a greater amount of lift on the advancing blade and if it isn’t compensated for the force imbalance will have the effect of tilting the disc backwards. Before the tilting occurs, there is a vibratory sensation and the helicopter will roll left. If the pilot doesn’t catch it, the forces will be so great as to cause a blowback and chop the tail off. That is the only time there is a dissymetry of lift on a helicopter.
To : You Will See
You wanted to know why the rotor head or the rigging procedures might have caused the rotor loss crashes which were all labled as pilot error just like all Robinson crashes. Just remember, if you are ever involved in a crash and your family brings a law suit against Robinson helicopters Frank Robinson wiil be their worst enemy.
Conflict of interest alleged in FAA crash investigations
By MARINA MALIKOFF
Sentinel staff writer
Of the dozens of R-22 accident investigations involving main rotor loss reviewed by the Sentinel, the National Transportation Safety Board frequently listed the probable cause as "undetermined" or pilot error — findings that do not surprise Palo Alto lawyer Michael Danko.
Because pilots and victims’ families are excluded from the investigation process, fault often is placed with the pilot, he said.
"Unfortunately, when there is a crash such as this and the NTSB wants to examine whether the aircraft is defective ... they call on all the manufacturers," said Danko, who is also a pilot. "They’ll ask Robinson if it is defective. To me, that is like asking the fox to find out what happened to the chickens."
Danko, whose firm is investigating a fatal August 1999 R-22 crash in Ireland nearly identical to the Watsonville crash in August, said the NTSB will "essentially staple their report to the technical report from Robinson, which will always point to pilot error."
NTSB accident investigations are conducted by what is known as the "party system," a process where the NTSB allows interested stakeholders, such as aircraft manufacturers and the Federal Aviation Administration, to join their crash probes. Anyone in a litigation position is excluded from the investigation.
The NTSB party system was the target of a 1999 study by the RAND Corp., a nonprofit public policy think tank. A RAND panel found significant potential for conflicts of interest when manufacturers are asked to police themselves.
The study, which was commissioned by the NTSB, recommended independent analytical and engineering resources assist in investigations "if (the NTSB) is to ensure its future independence and integrity," according to a statement issued by RAND when its report was released in December 1999.
The report was recently forwarded to the NTSB, where it is under management review, said NTSB spokeswoman Lauren Peduzzi. Recommendations and changes to the system will be considered, she said.
"The board’s mission is to investigate accidents, determine relevant safety issues and issue recommendations for improvements in order to prevent similar accidents from happening again," Peduzzi said. "Although the party process allows us to tap the manufacturer’s expertise with their equipment, the board’s investigators act as impartial leaders. ... It is their job to ensure that a fair and thorough investigation is conducted and that the probable cause accurately reflects the safety issues in the case."
Benjamin F. Venti, the father of a pilot who, along with two passengers, was killed in a Robinson R-44 crash in July 1993, was so troubled by the investigation into his son’s death, he appealed to his Los Angeles County congressman, Matthew Martinez.
Martinez contacted NTSB chairman Jim Hall, who appointed Venti an official member of the investigation team, contrary to NTSB policy.
Frank Robinson, president of Robinson Helicopter Co., said he and three others from his company had been on the team.
Evidence presented by Venti led the NTSB to revise its findings to show probable cause of the crash was a fatigue failure of the control stick assembly.
The report also found that lack of FAA oversight during the R-44 certification process may have contributed to the fatal crash.
The NTSB’s initial investigation had been hampered by a post-crash fire, which obscured evidence.
The RAND study also found that the 400-member NTSB staff simply doesn’t have the resources to thoroughly investigate each accident.
Jerry Sterns, whose Oakland-based firm specializes in aviation cases, agrees.
"The board does not have the budget nor the experts to do its job properly, so it is forced to rely heavily on outside people, who of course are supplied by the very companies being investigated," he said. "The companies many times drive the investigation, and the board has consistently refused to allow any representatives of the victims to participate and treats their lawyers as subversives."
However, Robinson, founder of the helicopter company, stressed that the NTSB investigator has full control over the crash probe, and that it would be impossible to conduct a thorough investigation without the manufacturer’s expertise.
"The manufacturer is not a theorist and is not allowed to touch anything at the site unless under the direction of the (NTSB) investigator," Robinson said. "He is there to identify the parts and has absolutely no input on probable cause."
In 1994, though, the NTSB learned that Robinson was serving as the quality assurance liaison to the FAA, raising concern of a conflict of interest during safety reviews.
Robinson confirmed he had served in that capacity — called the designated engineering representative — at various times over the years, and said it was "standard practice" in the industry for company officers to do so.
Robinson said he voluntarily resigned from that role four or five years ago. He now has three employees assigned to the job, one of whom is a company officer.
But accident investigations are still tainted by the cozy relationships that develop between FAA representatives and the manufacturers, according to several aviation law attorneys, who note that juries frequently reach conclusions about accident causes that are different than what the official investigators determine.
"In more than 50 percent of our cases, we have a cause that is different than the NTSB," said Richard Schaden, an attorney and aeronautical engineer. "The NTSB’s probable cause is heavily loaded on the pilot-error side."
When it comes to Robinson helicopters, that’s an appropriate finding, Robinson said.
"The fact remains that the vast majority of accidents do result from pilot error," Robinson said. "When they are used in training and by low (flying) time private pilots, it’s very high."
Those statistics don’t comfort families who have lost loved ones in Robinson crashes, said Danko, who maintains that a design flaw in the sensitive R-22 controls prevents flight instructors from responding quickly enough to prevent the crashes.
"History has shown the R-22 is not safe, and the fact is you have many high time pilots who have suffered the same scenario," Danko said. "You can’t blame all these accidents on pilots."
Aptos pilot Kent Reinhard and his student Gary Sefton died Aug. 18 when the rotor blades tore through the cockpit of Reinhard’s copter in midair during an instructional flight near Watsonville.
Reinhard, 57, had flown airplanes and helicopters for decades. He earned his first pilot’s license in 1961, and had logged thousands of flight hours — including 1,000 hours in the R-22 — at the time of his death.
In May 1996, Reinhard completed the Robinson Helicopter safety course and received an "average" rating — the most common rating, according to Robinson, who considers Reinhard a "high time" pilot.
Reinhard, a corporate pilot for Dole Food Co., operated a flight school out of the Watsonville Airport and was an R-22 stunt pilot with Showcopters, a Salinas-based air show team.
Sefton, 46, of Hollister, was studying for his airplane pilot’s license when he changed his focus to helicopters a year ago. The fatal flight with Reinhard was his first lesson.
Investigators from the NTSB, FAA and Robinson Helicopter Co. were at the crash scene the following day, along with local Sheriff’s Office inspectors.
The cause of the accident is still under investigation. The preliminary findings indicate loss of main rotor control is a factor, along with mast bumping, which is typically caused by abrupt input into the controls.
Reinhard’s sister, Jean Grace of Carmel, said Robinson’s position that pilot error likely caused the crash is predictable, but added that she is reserving judgment until the NTSB finalizes its report.
"From a liability standpoint, what else can (Robinson) say," Grace said. "At this point, we consider this a tragic accident."
Contact Marina Malikoff at
[email protected].
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The Cat