Aviation Accident Summaries

Aviation Accident Summary SEA02LA129

Crescent Lake, OR, USA

Aircraft #1

N690RE

Rockwell International 690A

Analysis

The pilot called the Oregon State Department of Aeronautics and was briefed on the conditions related to the 3,900 foot long, paved runway at Crescent Lake as well as the shifting wind conditions encountered at the airport. Upon arrival at the airport in the Rockwell 690A turboprop twin, the pilot set up for an approach to runway 31. The aircraft's GPS/Air Data computer indicated southwesterly winds at 7 knots and the windsock indicated southerly winds. He also reported that the windsock was indicating southerly winds at about half a sock. Approximately 30 feet above the runway threshold, in the landing configuration and at 90 knots, the pilot encountered turbulent/wind shift conditions. The stall warning sounded, the nose dropped, and indicated airspeed dropped abruptly from 90 knots to about 80 knots. The pilot applied full power and pitched the nose up about 15 degrees but was unable to arrest the descent rate during which the empennage impacted the runway surface slightly north of the displaced threshold. The aircraft 's nose wheel struck the runway immediately thereafter, and the nose gear separated with the aircraft skidding approximately 1,300 feet down the runway to a stop. There were no published restrictions for the use of either runway 13 or 31.

Factual Information

HISTORY OF FLIGHT On July 15, 2002, approximately 1210 Pacific daylight time, a Rockwell International 690A, N690RE, registered to Oregon Lifestyles Realty, Inc., and being operated/flown by a private pilot, sustained substantial damage during a hard landing and nose gear collapse while landing at the Crescent Lake State airport, Crescent Lake, Oregon. The pilot was uninjured. Visual meteorological conditions existed and no flight plan had been filed. The flight, which was business related, was operated under 14 CFR 91, and originated from Redmond, Oregon, approximately 1150. An inspector from the Federal Aviation Administration's Hillsboro, Oregon, Flight Standards District Office interviewed the pilot on the morning of July 16th. The pilot reported that he was on a short final to runway 31 when the wind direction shifted. The aircraft developed a rapid sink rate and landed hard striking the empennage first and then the main gear. When the nose gear made contact with the runway it separated. The aircraft skidded down the runway and came to a stop (refer to Attachment FAA-I and photographs 1 and 2). The FAA inspector asked the pilot if he had contacted Oregon State Aeronautics (as suggested in the current Airport/Facility Directory) and the pilot indicated that he had done so. The pilot also indicated that he was not aware of the Oregon Department of Aeronautics website reference to "State Warning Airport" that provided specific information related to Crescent Lake (refer to Attachment SWA-I). The FAA inspector contacted Oregon State Aeronautics and determined that the state contact advised the pilot, when he called, of the shifting wind conditions at the airport (refer to Attachment FAA-I). The pilot subsequently reported in greater detail (refer to NTSB Form 6120.1/2) that prior to departing he contacted Oregon State Aeronautics for current airport information. He indicated that he had flown into the Crescent Lake airport previously in single-engine aircraft. Upon arrival he entered the pattern and set up for an approach to runway 31. He reported that the windsock "...indicated southerly winds, about half a sock...." He also reported that the aircraft's air data computer and GPS system indicated southwesterly winds at 7 knots. He set the airplane up in landing configuration with full flaps and reduced airspeed to 90 knots on one mile and crossed the tree line approximately 100 feet above the end of the runway. He reported that approximately 30 feet above the runway surface "...the aircraft encountered a moderate burble of turbulence, the stall warning sounded, the nose dropped, and indicated airspeed dropped abruptly from 90 knots to about 80 knots...." The pilot applied full power and pitched the nose up about 15 degrees but was unable to arrest the descent rate during which the empennage impacted the runway surface slightly north of the displaced threshold (refer to photograph 3). He then cut power with the nose about 15 feet above the runway and the aircraft contacted the runway again, the nose wheel impacted and the nose gear separated. The aircraft continued down the runway approximately 1,300 feet before coming to a stop (refer to photographs 4 and 5). AIRCRAFT INFORMATION The pilot reported departing Redmond with 1400 pounds (~200 gallons) of fuel. This fuel load, combined with a generic 6,300 pound aircraft empty weight and 200 pounds generic pilot weight resulted in a approximate hypothetical 7,900 pound weight at landing (not counting fuel burn on the flight). Landing distance from a 50-foot height for the 690A aircraft was discussed in the flight manual and could be determined as a function of outside air temperature, pressure altitude, aircraft (landing) weight, and wind component (refer to Attachment FM-I). The zero thrust stall speeds for the 690A aircraft were discussed in the flight manual and could be determined as a function of weight and angle of bank (refer to Attachment FM-II). METEOROLOGICAL INFORMATION The pilot reported the estimated temperature at the time of the accident as 78 degrees Fahrenheit (25.5 degrees Centigrade). The pilot also reported light turbulence and winds from the south at 7 knots. The density altitude at Crescent Lake State was estimated to be approximately 7,000 feet. AIRPORT INFORMATION At the time of the accident the Crescent Lake State airport runway had been paved for its full length and width of 3,900 feet by 30 feet. Runway 31 had a 275 foot marked, displaced threshold leaving 3,625 feet of available landing runway. The airport was 4,810 feet above mean sea level. The controlling obstruction for runway 31 was reported on the FAA Airport Master Record (FAA Form 5010) on 11/21/2002 as trees 55 feet in height on centerline and 336 feet from the displaced threshold (refer to Attachment 5010-I). This was the same controlling obstruction as that in existence on the date of the accident as shown in the 11/02/1999 Airport Master Record schematic (Attachment 5010-II). Trees measuring 80 feet in height lined both sides of the runway beginning about 180 feet left and right of the centerline (refer to photographs 4 and 5). A single windsock serves the Crescent Lake airport and is situated slightly east of the threshold of runway 31 (refer to photograph 3). There were no published restrictions on the use of either runway 13 or 31 at the airport.

Probable Cause and Findings

The pilot's failure to maintain proper rate of descent resulting in a hard landing and subsequent nose gear separation. Contributing factors were the turbulent crosswind conditions the pilot encountered just before touchdown.

 

Source: NTSB Aviation Accident Database

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