ASN Wikibase Occurrence # 187161
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| Date: | Tuesday 10 May 2016 |
| Time: | 12:15 |
| Type: |  Beechcraft B24R Sierra |
| Owner/operator: | Private |
| Registration: | N2052L |
| MSN: | MC-437 |
| Year of manufacture: | 1976 |
| Total airframe hrs: | 1461 hours |
| Engine model: | Lycoming IO360 SER |
| Fatalities: | Fatalities: 0 / Occupants: 2 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Pine Mountain Lake Airport (E45), Groveland, CA -
 United States of America
|
| Phase: | Take off |
| Nature: | Private |
| Departure airport: | Groveland, CA (E45) |
| Groveland, CA (E45) | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
The passenger, who was a student pilot, recently purchased the airplane in an estate sale. He and the airline transport pilot, both of whom lived in Mississippi, had traveled to California to retrieve the airplane and fly it back to Mississippi. Before the purchase, the airplane had not been maintained, operated, or flown in almost 11 years. Following the purchase, the owner contracted with a mechanic in California to ensure the airplane was in airworthy condition, which the mechanic reportedly did. The day before the accident, the pilot and owner took the airplane for its first flight after its dormant period and flew one uneventful circuit in the airport traffic pattern, as planned. The following day, the pilot and owner planned to fly the airplane for some systems evaluations. During that takeoff attempt from runway 9, the airplane became airborne but failed to climb and struck trees and terrain beyond the runway end. Although the pilot believed that he was taking off into the wind, witness statements and other evidence indicated that the takeoff was attempted with an approximate 5-knot tailwind. The first 1,000 ft of the runway was level, but the remaining 2,000 ft was sloped uphill. Although the Pilot’s Operating Handbook specified using 15° flaps for takeoff, and the pilot reported that he used that setting and did not alter the flap position during the flight, the flaps were found to have been fully retracted at impact.
Surveillance camera imagery captured about 2 seconds of the flight, when the airplane was about midfield and 4 ft above ground level (agl). Review of that imagery and audio data indicated that the ground speed was about 68 knots and that the engine speed was about 2,640 rpm; both values were consistent with normal takeoff values. However, the exact winds (and thus airspeed) were unknown, and because the propeller was a constant-speed model, nominal takeoff rpm could be achieved even if the engine was not developing full-rated power.
Detailed examination of the airplane, including the engine, revealed that, although its condition was not in accordance with Federal Aviation Administration and manufacturer guidance, none of the observed deficiencies could have caused or contributed to the loss of climb performance, except for one magneto that was found to be mistimed to the engine by 7°. Evidence suggested that this was likely a result of the accident but that could not be determined with certainty. Performance calculations conducted by the airplane manufacturer, which accounted for most of the known takeoff conditions, including fully retracted flaps, indicated that the distance to 50 ft agl was slightly more than the available runway. The estimated airplane takeoff weight was about 300 lbs (11%) below the maximum takeoff weight that was used in the calculations, which would yield better performance than the calculated results. However, those calculations did not account for off-nominal values of the many other variables that could adversely affect takeoff performance, including pilot technique, airframe and engine deterioration, and inaccurate or improperly set instrumentation and controls. Thus, although a successful downwind takeoff with no flaps was unlikely, it might have been possible, but there were too many other unknowns to determine its likelihood with greater certainty.
The reason(s) for the retracted flaps could not be determined. It is possible that the pilot forgot to extend them or that they were inadvertently and unknowingly retracted. Given the location of the flap control switch and its design (momentary, paddle-type), it is possible that the pilot extended the flaps to the proper takeoff setting of 15° but that they were subsequently retracted when the nonpilot passenger inadvertently contacted and actuated the flap control. The size and location of the flap position indicator gauge, combined with the location of the flaps (behind the pilot on the low-wing airplane), minimized the possibility that the pilot would notice that they had been retracted.
Probable Cause: The pilot's decision to conduct an upslope, downwind takeoff combined with an improper flap setting, which resulted in the airplane's inability to clear trees beyond the runway end. The reason for the improper flap setting could not be determined.
Accident investigation:
 |
|
Sources:
NTSB
FAA register: http://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?NNumbertxt=N2052L
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 10-May-2016 22:17 | Geno | Added |
| 11-May-2016 13:39 | Anon. | Updated [Narrative] |
| 21-Dec-2016 19:30 | ASN Update Bot | Updated [Time, Damage, Category, Investigating agency] |
| 08-Sep-2017 19:47 | ASN Update Bot | Updated [Other fatalities, Departure airport, Destination airport, Source, Narrative] |
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