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ASN Wikibase Occurrence # 126508
Last updated: 18 February 2019
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Date:27-DEC-1976
Time:11:45
Type:Silhouette image of generic PA34 model; specific model in this crash may look slightly different
Piper PA-34-200 Seneca
Owner/operator:Robertson Aircraft
Registration: N33589
C/n / msn: 34-
Fatalities:Fatalities: 0 / Occupants: 1
Other fatalities:0
Aircraft damage: Written off (damaged beyond repair)
Category:Accident
Location:Verlot, Washington -   United States of America
Phase: En route
Nature:Test
Departure airport:Renton Municipal Airport, Renton, Washington (RNT/KRNT)
Destination airport:Renton Municipal Airport, Renton, Washington (RNT/KRNT)
Investigating agency: NTSB
Narrative:
Written off (destroyed) December 27, 1976 when broke apart over Verlot, Washington, in flight during flutter clearance flight tests. Aircraft broke apart at 250 mph immediately after elevator down phase. The pilot - the sole person on board - bailed out and parachuted to safety. According to an eyewitness report from the pilot of N33589:

"The flutter testing flights for the Piper PA-34 N33589 were not felt to be very dangerous because of our previous success with the Seneca. In fact, I had just completed a series of flutter flights on a Seneca II equipped with Robertson spoilers and tip tanks. The accelerometer traces were good, but the camera that recorded the speeds and altitude malfunctioned. The owner was impatient and wanted his aircraft, the FAA wouldn’t accept our data without speed verifications, and by the time the bad film had been developed the aircraft was reconfigured and ready for delivery. The FAA allowed us to deliver the aircraft with some restrictions, including that flutter testing still needed to be completed.

The intended test was to climb to 25,000 feet, with camera and recorders on and to pulse each control at several predetermined speeds and at Vd (10 per cent past red line). The first flights (on December 24th 1976) were aborted because low temperature (-45 degrees F) at 25,000 feet froze the elevator jackscrew and only low-speed data could be collected. The heavy grease was removed from the jackscrew and a light silicone spray was used instead.

Flight tests on December 27th appeared to be going well. I climbed to 25,000 feet on an IFR clearance above a 4000 to 6000 foot broken cloud cover. The test equipment turned on and trim function was good. Intermediate speeds looked good and at Vd (250 IAS), at approximately 20,000 feet, I completed the following control pulses: aileron (spoiler-equipped) left and right, rudder left and right, elevator down, and then I reached to start the up-elevator pulse. The aircraft was in trim and my left hand was holding the wheel lightly. The air was smooth and there had been no vibration.

It felt like an explosion; the elevator failure resulted in an extremely violent nose-down tumble. Both wings tore off, firstly outboard of the engine nacelle, then again at the fuselage. The fuselage was ruptured, parts of the tail section and rear door were gone, the fibreglass nose section was gone and the windshields were blown out. Negative Gs had me pinned against the cabin ceiling, the violent shaking had torn off my helmet, and I had to protect my head with my hands to keep from being knocked out.

The survival instinct had taken over. I knew I had to get out of there to stay alive, but I couldn’t move and couldn’t do anything except try to protect myself against the beating I was taking. As abruptly as it started, the violence stopped. It was smooth and calm, with a sense of slow rolling or tumbling. The cold air (-40 degrees F) was blowing through the hulk of the fuselage. Seat belt off and out through the cabin door. I opened my chute immediately, which could have been fatal. As my chute opened, an engine with a section of wing dropped past me. I can still clearly see that engine in my mind. The prop was feathered and the engine was running. The total sequence of failure and getting out only took seconds, but it felt like minutes.

I was awed by the destructive disintegration of that aircraft and my miraculous survival. I was now floating down at 20,000 feet or so, with small light pieces of aluminum, insulation and fabric all around me. In whatever direction I looked I could see confetti.

This was December and I was over a cloud layer somewhere above the Cascade Mountains of Washington. I really wasn’t dressed appropriately and again my thoughts turned to survival. Luck truly was on my side that day. Wear some torn clothes, a parachute under your left arm, put up your thumb and you get a ride every time."

Sources:

1. NTSB Identification: SEA77DYE06 at https://www.ntsb.gov/_layouts/ntsb.aviation/brief.aspx?ev_id=55583&key=0
2. FAA: http://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?NNumbertxt=33589
3. http://www.flightsafetyaustralia.com/2014/09/be-still-my-fluttering-seneca/
4. http://planecrashmap.com/list/wa/


Revision history:

Date/timeContributorUpdates
30-Nov-2016 22:15 Dr. John Smith Updated [Aircraft type, Cn, Operator, Location, Nature, Departure airport, Destination airport, Source, Narrative]

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