Redline Vs. Stabilator Torque Tube

[Tom Corell]

Check This Out:
http://www.youtube.com/watch?v=pEOmCkZy ... _embedded#!
Coments Please.
Tom C.

[Zach Grant L1011jock]

Tom,
Yes this happened! Cir. 1969-70 I think. Fred Haise (NASA test pilot and astronaut of apollo 13 fame) was the pilot. The aircraft was 20% over red line in a dive, with agravated conditions (the yoke was being excited). After multiple attempts, they finally got one to go to full cyclic flutter. Note buckling in the aft fuselage section. Aircraft was repaired as the aft bulhead was cracked, but no damage was noted in the tail assembly, only near the interface to the fuselage. Sad note, this aircraft survived until the 80's when it crashed, killing 4 due to fuel exhaustion, a totally stupid and preventable situation.
-Zach

[Chief]

Tom,

I've seen the video, interesting. Didn't know all that Zach addeed, but it makes me feel ever better about our planes.

By the way, great article in this month's Aviation Safety magazine. It speaks in great detail about True Airspeed, Indicated Air Speed, etc. Very educational. You can get in a dangerous situation with the Airspeed Indicator below yellow or red lines. Just something to think about. How important is it to be 5 minutes faster to your destination?

We have a 250, a great bird, and it is faster than driving, I am committed to be more conscious of speeds after reading the Aviation Safety article.

Just a thought!

[Zach Grant L1011jock]

Brett,
You bring up a good point. Flutter is a function of Mach, or in other words true airspeed adjusted for current mach. In small aircraft operating below 18K feet, the published Vne as a fixed number is usually OK. The margine between bad things and normalcy do get significantly smaller as you get into the higher altitude/higher TAS range of the flight envelope. This is part of the reason why Turbine aircraft have no yellow arc as Vne is set at the top of the normal operating airspeed range. It is also why most turbine aircraft certified to higher altitudes have a movable "barber pole" indicator that reduces the top limit of the Vne as the Mach speed increases vs. IAS. It is of note that the Turbo Twin Comanche has a reduced Vne above 20K' due to this penominon (Rayjay AFM Suppliment).
-Zach

[Tom Corell]

Zach,

Thanks for your input educational as usual,I agree with Brett I feel even better about the structural strength of our airplanes.
Tom c.