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Although I did not know these 2 apparently good, fine gentlemen, my heart goes out to their families.
It is easy to explain away and discount crashes that occur in bad thunderstorms or when people do stupid things or commit obvious errors. However, when 2 competent pilots apprently fall out of the sky in vfr conditions, answers must be sought. I trust in due time we will learn the truth.
I appreciate the input of those much more knowledgable than I-thanks Charlie, Brent, Jeff, etc.
Charlie, I agree that it must seem obvious to anyone who has been involved in building a IV that the area of the fuselage behind the gear doors where the A/C holes that you reference are made has to be the weakest area of the fuselage. We installed Mike Custard's vertical fin extension to give better yaw stability(in addition to the strakes) on my propjet and unscientifically to my eye, this seems to beef up this area though from the top rather than the underside. If any structural testing takes place I think that this modification should also be tested to see if it helps. Thoughts?
I hate to render unsubstantiated opinions but Lynn, I wonder if a practice emergency descent could cause the plane to have unexpectedly surpassed Vne. Just a thought as on fast descents at "lower" altitudes Vne can come quickly in a propjet.
Fly Safe,
David Weinsweig
weinsweigd@gmail.com N750DW Propjet
charliekohler@yahoo.com 5/1/2012 9:56:12 AM >>>
Lynn I have raised the issue regarding the holes cut in the aft fuselage for the air-conditioning for several years. Several years ago I sat at a table with Martin Hollman, and Tim Ong and we talked in general about gross weight increases over the years, modifications to the fuselage, etc. etc. Martin agreed at that time that the only solution was to have a new stress and flutter analysis performed.
He raised a red flag regarding the AC holes. I would suggest Lancair together with Lancair IV owners initiated a stress and flutter analysis of the current state of the fleet. Turbines/IVP's with winglets etc. etc. considering newly recommended the gross weights and airframe modifications.
Brent very ably addresses the issue when you are facing weather and you know you have a fragile airframe that you have cut two large holes in. Here is his letter regarding another accident in which all the blame goes to the weather. I can think of several others that faced--- something---- and did not fly out the other side. I wonder, if they had a sound airframe going in. The latest accident has me questioning---just how bad was this weather that caused airframe to come apart? Was airframe capable of handling 3G-5G ??
Reread Brent Reagan's post from the Lancair list.
To all Lancair Pilots;
Late last month I was contacted by the NTSB in Atlanta regarding the crash of N29ME. It seems that there was an CFS EFIS-2000 system installed in the airplane and they had recovered the IDUs from the wreckage. They had learned from Kirk that the IDUs contained logs of the last few flights and asked if I could recover the data for them.
I received the IDUs late last week and although the units had been severely damaged I was able to remove the flash data card from the MFD and, after some repair work, extract the log files.
The investigation into this accident is ongoing and detailed public discussions of the data and conclusions should be reserved until the NTSB final report is issued. However, this report is some months away and there are two generic safety issues that that I would like to discuss in the hope of improving flight safety during this thunder storm season.
From the Preliminary report:
The last flight left Portland Indiana at 15:45 eastern daylight time and proceeded normally for just under two hours when, at 17:30 the pilot requested a left deviation for weather. The deviation was not granted until approximately 8 minutes later when the pilot then turned right 70 degrees and remained on that course for 11 minutes while he descended from 17,000 to 13,000 feet. The plane then turned left, back on course. Clearance was given to 11,000 feet and the last communication was at 17:49. The last radar contact was at 17:55 at 11,700 feet. Level 5 thunderstorms were reported in the area.
The data log records the conditions of flight once every 5 seconds. A new data log is created when the system starts in flight mode and continues recording until power is interrupted or the system resets. The last 8 data points of the flight (35 seconds) show that while cruising at 187 KIAS the the nose pitched up 20 degrees and the plane climbed to 12,436 at a peak of 5,328 fpm and banked left 50 degrees (imagine a wing over). At 113 KIAS the nose pitched down 29 degrees below horizontal with a left bank angle of 80 degrees. The G meter never goes negative but a large drop in oil pressure indicates that it may have been negative between data points.
The plane is in a steep left spiral dive with the peak rate of decent reaching 12,685 fpm. OAT is falling from 35 degrees F to 27 degrees F. Engine power remains unchanged from the cruise setting of 70% and 2,400 rpm. G forces are rising as the nose starts to come up.
The last data point is at 9,146 feet with the plane pitched down 35 degrees (decreasing) and banked left 71 degrees (also decreasing). Decent rate is 10,208 fpm and airspeed is 253 KIAS. The airspeed is increasing at 7.1 knots per second and at this rate Vne will be reached in less than 3 seconds. The G load is 3.75 Gs positive (it had climbed from 0.68 Gs in the last 10 seconds). Within 5 seconds an event occurs that an observer on the ground hears and describes as an explosion...
I can not say what actually happened in this case. We can consider a hypothetical scenario as a way to better understand the dynamics of flight. Imagine that the plane flew through an updraft / downdraft wind shear. A sudden drop in OAT can indicate a downdraft. While in the downdraft, the ground track shows the plane reversed course with the final data point being just before re-penatrating the downdraft / updraft interface. It is easy to imagine that the wind shear could apply the additional loads needed to fail the wings.
Besides the sorrow of loosing four souls, members of the Lancair community, there are two things that are, in my view, most apparent. The pilot requested a deviation for weather that the controller did not grant due to traffic. "Weather" in this case was level 5 thunder storm cells. I cannot say what the pilot should have done but he did have the option of saying "unable" or "I am declaring an emergency and turning left". Controllers are sitting safe and snug on the ground. The pilot is responsible for the safety of the flight regardless of what the controller says. If you are in an unsafe situation, do whatever you need to do to change problems that must be solved in the air to problems that can be solved on the ground. The worst administrative action is far better than the best funeral. The second apparent thing is that if you know you are about to get, or are being, knocked around, get your speed down under Va and keep the wings level. Pitch for speed and power for altitude. Never dive for an assigned altitude. We all know these things but it can't hurt to review them in your mind to reinforce the understanding of your responsibilities as PIC.
My deepest sympathies and heartfelt condolences go to the families and friends of the victims.
To everyone else, fly safe, please.
Regards
Brent Regan
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My inspections over the years have brought several areas of weakness to light. I would suggest all owners check their airplanes for a debonding of the skin between the very aft end of the main landing gear doors. Also check for structural security and construction of the box that surrounds the elevator push tube. With someone's help, go to the tail tiedown area and push up with your back. You will see movement of the skin if there is a debond. Quite often when I have discovered this I asked the owner if he was a self-taught pilot? And did he have any hard landings? Most admitted it. I recall one case (pre-Buy) in Northern California where the owner refused to consider fixing this situation to effect the sale. He didn't think it was a big issue at all.
Additionally I suggest you read http://www.vansaircraft.com/pdf/hp_limts.pdf Charlie K.
See me on the web at www.Lancair-IV.com ________________________________
From: Lynn Farnsworth <farnsworth@charter.net>
To: lml@lancaironline.net Sent: Wednesday, April 25, 2012 4:24 PM
Subject: [LML] Re: Harry League & Pat Franzen fatal IVPT accident 4/23/2012
Subject:Harry League & Pat Franzen fatal IVPT accident 4/23/2012
It is my sad duty to report Mr. Harry League and Mr. Pat Franzen were killed yesterday when the IVPT, N66HL, [Lynn Farnsworth] It appears to me that the aircraft disintegrated in-flight. What kind of flight profile would include doing training that would lead to an in-flight breakup?
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