----- Original Message -----
From: Dennis Lithgow
Sent: Monday, November 23, 2009 12:23 PM
Subject: [ultracruiser] Update from Terry
I got the following message from Terry today and he cleared it for distribution:
I got your message last night then Roy Breaton called this morning. A quick recap:
I rec'd the failed section of Roy's spar Monday last week. I knew the lab couldn't test it until after Thanksgiving, so we did a little detective work on our own. First we broke a couple pieces of spar material in an attempt to duplicate the edge of the break. We were assuming a forward movement of the wing due to a high angle of attack. This proved to be true, on the second sample, bending the spar forward and slightly up, the break was nearly identical. We couldn't tell from the pictures what the rear spar looked like after failure. So, on Tues. I asked Roy to send us pictures of the rear spar as it attaches at the fuselage.
| This morning Roy called with his findings. Roy
had installed a "mock up" piece in place of the 3/4x3/4x1/8 6061 to allow him
to keep building while the material was on order. Unfortunately he forgot to go
back and install the proper material. He had used a piece of 2024 .016 sheet
bent into an angle.
I am amazed it held together after the ground loop and prop strike. And there are a hundred more questions.
Most importantly Roy is recovering and even mentioned buying a materials package to get started on another UC. He was also very apologetic for causing any disruption to our business.
Dennis I will post this on the Hummel forum. If you want to forward it to the Yahoo group is fine with me.
Thanks for you patience with us,
The crash of the Hummel UltraCruiser earlier in 2009 demonstrated
the integrity of the wing connection to the fuselage. The wing
in flight. The pilot reported a loud bang. He then saw the
wing fold. He blacked out. Other reports place the aircraft at 50
to 75 feet from
the ground. The crash occurred during the 3rd circuit. Additional
reports indicate the failure was at the wing root.|
Note: I am not identifying the people until permission is granted.
I received the following report on the pilot, "His wrist was pretty bad and also his left foot. They have put a pin in his wrist and are letting the swelling go down from his foot to fix it. He will likely be in the Hospital for a few more days. He is in good
spirits though and will be taking a few months off to recover" [w]
Links to news report
cnews ... Pilot survives ultralight plane crash
Correction:Immediately after the accident, I was approached by an operator at the airport for comment. My first conclusion was incorrect. [S. Steve Adkins]
"The piece that you thought was the spar cap in photo 1639 is one of the fuselage side stringers that was bent into the spar. I bent it out of the way for some of the other pictures." [w].
"We think that the 6061T6 material is the side rail not the spar cap. Since there are no holes in the top [as would be true for the spar cap]. That is not to say that the spars are correct but we can't tell from the photos. We believe, even if the spars were 6061T6 it should not have failed unless there is some other major construction issues." [m]
The wing spar appears to have been built out of the correct material.
Photos from the Hummel Aviation Website during stress testing:
Interior The center carry-thru support on the right side buckled under compression.
Full Series of Stress Testing Photos
Material Testing performed by Steve Adkins and Dale Johnson
Note: Right wing moved around to facilitate extracting pilot.
This view show the protection provided by the structure.
|For comparison ... test setup at Hummel Aviation:|
The center carry-thru support on the right side buckled under compression.