Question for any seasoned Hawker 800XP captain?

Question

On my 2nd trip as captain on my companies Hawker800, while descending out of 410 the right hand T/R came unlocked...following the checklist we disarmed that T/R.

Now, according to Hawker/Beech this is all that is required.

However, out of 390 at around .75 mach the airplane started buffeting...violently...oscillation started in the pitch axis...Pulled the throttles back....slowed to .73...the oscillation stopped...

Once we transitioned to IAS we could not exceed 280 knots.

There was no Auto Stow annunciator on the MWS panel.

My question is: If the T/R came out even a little..could it cause enough airflow disruption to blanket the elevator of the airplane and cause this oscillation? Or do I need to get maintenance to check the tail for something that I may not have seen?

Keep in mind this is something that Flight Safety has never heard of happening and they had no answer for me...

A typical abnormal condition that we will never see in our training...

Jonathan S

Answer 1

Not a Hawker driver but if your reverser deployed, even a tiny bit, that could certainly cause a pretty mean buffet...

Look at the vortex generators on pistons....  Just the slightest bump on the laminar wing and suddenly the AC is 61kt stall compliant. The aerodynamics is a science that I cannot comprehend fully.

You should ask Peter Garrison at Flying magazine.

www.flyingmag.com

He's the nerdy type that can actually explain the phenomenon.

And yes, you should always write-up anything that bothers you.

And if FlightSafety is clueless to this, you should also see to it that the folks at Hawker/Beech know about it.