History of Flight
On March 19, 2011, at approximately 1140 Pacific daylight time, a Beech G35, registration N4211D, sustained substantial damage during a recovery from an unintended unusual attitude near Whidbey Island, Washington. The certificated private pilot, who was the owner, was not injured. The personal flight was conducted under Title 14 Code of Federal Regulations Part 91 in visual meteorological conditions; no flight plan was filed.
The pilot reported that he was cruising at 4,500 feet and correlating indications of two panel-mounted navigation receivers. A handheld GPS was mounted on the control yoke. Noticing he was about to enter Restricted Area R-6701, he initiated a right turn with an estimated bank angle of 45 degrees. During the turn, he glanced at the GPS to verify clearance. When he looked back, the bank angle had increased to about 75 degrees right wing down, and the pitch attitude was about 20 degrees nose down, with airspeed at 190 mph (in the yellow caution range).
He leveled the wings and initiated a pull-up, during which he heard three or four rapid "thumps." After recovering to level flight, the airplane flew normally. The pilot flew cautiously back to his home field and landed without further incident. Post-flight inspection revealed wrinkled and torn aft fuselage skins.
Pilot and Aircraft Information
The pilot held a private pilot certificate with single-engine, multi-engine, and instrument ratings, and reported about 1,188 total flight hours, including approximately 592 hours in the accident make and model. His most recent flight review and FAA third-class medical certificate were both completed in June 2010.
The airplane, manufactured in 1955, was first registered to the pilot in 1990. It featured a V-tail configuration with post-delivery capture fairings ("cuffs") and two ruddervators, each with a trim tab. The ruddervators were reskinned and rebalanced in January 1997. Airworthiness Directive 94-20-04-R2 was accomplished in February 2004, requiring verification of ruddervator balance and inspection of the empennage and control system. No subsequent cable tension or rigging checks were documented. At the most recent annual inspection in August 2010, total time in service was 4,257 hours; at the accident, it was 4,261 hours.
Meteorological and Navigational Details
A weather observation at 1153 from the pilot's home airport (about 10 miles south-southeast) reported wind from 180 degrees at 7 knots, visibility 10 miles, scattered clouds at 3,200 feet, temperature 8°C, dew point 1°C, and an altimeter setting of 29.75 inches of mercury.
The Seattle sectional chart depicted R-6701 up to 5,000 feet msl, with intermittent activation by NOTAM and 2 hours' advance notice. The pilot had not confirmed whether R-6701 was active; he believed it was "normally not active on Saturday." No evidence showed he checked NOTAMs or was in contact with air traffic control. The panel-mounted VOR instruments could not readily depict the restricted area boundaries, but the handheld GPS showed them.
Examination and Findings
An FAA inspection three days after the event found three primary damage sites: a diagonal wrinkle about 2 feet long on the aft right fuselage, crumpled skin on the aft left fuselage, and separated bottom skin at a lap joint. No pre-event damage or corrosion was observed. A cockpit g-meter registered a maximum of about 2.5g and a minimum of -0.7g.
About six weeks later, a detailed examination revealed a small buckle on the lower outboard skin of the left ruddervator, but no other visible damage to the stabilizers or control surfaces. Control cable routing, condition, and operation appeared normal. Control surface travel measurements showed discrepancies: left and right up-elevator travel were 2.1 and 2.9 degrees less than specification, respectively; right down-elevator travel was 1.1 degrees greater; left and right down-elevator tab travel were 1.5 and 0.1 degrees greater, respectively. Travel ranges were asymmetric between left and right sides.
According to the airplane's certification basis (CAR Part 3, Normal category), maneuver limit load factor was 2.1 (ultimate 3.15). Maneuvering speed (Va) was 130 mph, and maximum structural cruising speed (Vno) was 175 mph. The pilot reported applying about 2g at 190 mph (above Vno). The V-G diagram indicated that structural damage due to flight loads was possible or likely under those conditions.