SAIB CE-11-17

[F9DXER]

Interesting information.

Taken from AOPA's website

Think you know your V-speeds? The FAA has released a special airworthiness information bulletin (SAIB) providing information to pilots after determining from a crash investigation “that many pilots have a misunderstanding of what the design maneuvering velocity (speed), VA, represents.”

The investigation followed the Nov. 12, 2001, crash of American Airlines Flight 587, which killed all 260 people on board and five people on the ground. The NTSB determined that the vertical stabilizer separated in flight “as a result of the loads beyond ultimate design loads that were created by the first officer’s unnecessary and excessive rudder pedal inputs.”
“Many pilots believe that as long as the airplane is at or below this maneuvering speed, they can make any control inputs they desire without any risk of harm to the airplane,” the FAA said in the SAIB. “This is not true.
“The design maneuvering speed (VA) is the speed below which you can move a single flight control, one time, to its full deflection, for one axis of airplane rotation only (pitch, roll or yaw), in smooth air, without risk of damage to the airplane.”
The SAIB states that even though the accident aircraft was operated under Part 25, the concept of maneuvering speed is relevant to all types of airplanes. It explains that the regulations governing airplane structure design strength require adequate strength for full control deflection below VA—but that manufacturers are not required to make airplanes strong enough to withstand full control input in one direction followed by full input in the opposite direction, or for more than one full control input.
This type of education—bridging the gap between what manufacturers test and what pilots think they test—was among the recommendations provided by an industry study of the certification process for Part 23 aircraft. AOPA chaired the study’s pilot interface working group that discussed flight testing, operation, and pilot training, and found a disconnect between aircraft certification and operation. In 2009, the group suggested more emphasis on pilot understanding of V speeds and the protection actually given at those speeds, among other recommendations.
The SAIB also explains that the VA number published in an airplane flight manual or pilot’s operating handbook is valid for operation at a specific gross weight, typically max gross weight. VA decreases as the airplane’s weight decreases. It recommends pilots reduce VA when operating below gross weight according to the following formula: VA-NEW = VA √(WNEW­/WMAX-GROSS).




Here is the SAIB link

http://rgl.faa.gov/Regulatory_and_G...aa64a2827e8625781c00744393/$FILE/CE-11-17.pdf

 

[BobDDuck]

Nice to see they are still hanging the AA crew out to dry despite the NTSB pointing out that it was AA's policy to use full rudder inputs to dampen out wake turbulence.

That said, there are a lot of people that think you can make multiple full scale inputs at Va and still be ok so maybe this article is useful to some.

As it said, Vs certification is based on single axis, single control, single time.

 

[Roger, Roger]

Nice to see they are still hanging the AA crew out to dry despite the NTSB pointing out that it was AA's policy to use full rudder inputs to dampen out wake turbulence.

I fail to see how "the vertical stabilizer separated in flight as a result of the loads beyond ultimate design loads that were created by the first officer’s unnecessary and excessive rudder pedal inputs." is hanging the crew out to dry.

 

[BobDDuck]

Because the crew was taught to use full rudder inputs. That was AA policy. The term "unnecessary" basically says "the crew should have known better". It's how things go. Under the current system, unless a wing just comes off in flight, the crew is going to be responsible. Always.

 

[Pépé le Pilot]

It would be interesting to see what the A300 FCOM says about full rudder deflection in flight. I have the A320 FCOM but not the A300...

 

[Roger, Roger]

Because the crew was taught to use full rudder inputs. That was AA policy. The term "unnecessary" basically says "the crew should have known better". It's how things go. Under the current system, unless a wing just comes off in flight, the crew is going to be responsible. Always.

Read into it what you will, but it comes across as paranoia to me. The rudder inputs WERE unnecessary, as the aircraft would have recovered from the wake encounter just fine without them. They WERE excessive, as they ripped the vertical off of the airplane. As I understand it, the NTSB did address AA's training procedure. Taking a lesson from that crash and using it to demonstrate a common misconception to people outside of the 121 world hardly comes across as crucifying the crew.