Aviation Accident Summaries

Aviation Accident Summary SEA98LA012

PORTLAND, OR, USA

Aircraft #1

N700HS

Aerostar PA-60-700P

Analysis

The pilot reported that during 'the mid stage of the takeoff roll...I experienced one or two asym[m]etrical surges that caused the plane to yaw to the right.' The pilot stated he corrected these with nosewheel steering (the pilot's operating handbook states not to use nosewheel steering during takeoff). The pilot stated, 'As I approached rotation speed, there was a strong yaw to the right....I believed...the nosewheel [had deflected]...full right....I then pulled back on the yoke to pull the nosewheel off....I became airborne...I heard the stall warning. The plane then veered sharply to the right, going off the runway....' Post-accident examinations of the aircraft's right engine and propeller revealed no evidence of pre-impact engine or propeller mechanical malfunctions. Directional control on the ground is available in the accident aircraft via differential braking, differential power, and rudder, if nosewheel steering is not available. While the pilot reported he had recently flown the accident aircraft with another pilot (not an instructor) to 'review aircraft systems and check my pilot competencies', his last documented flight review was 6 years before the accident.

Factual Information

On November 7, 1997, approximately 1245 Pacific standard time, an Aerostar PA-60-700P, N700HS, departed the south side of runway 10L during an attempted takeoff from Portland International Airport, Portland, Oregon. After departing the runway surface, the airplane struck runway lights and airport signage and caught fire. The private pilot-in-command, who owned the aircraft, and one passenger escaped the aircraft uninjured. The aircraft was substantially damaged in the crash and ensuing fire. The 14 CFR 91 business flight was on an instrument flight rules (IFR) flight plan, with a destination of Prineville, Oregon. Visual meteorological conditions prevailed at the time of the accident. The pilot reported that he departed behind an "Alaska Airlines Boeing 727 or 737" (NOTE: Alaska Airlines operates Boeing 737 [B-737] and MD-80 aircraft.) He stated that after the Alaska Airlines jet departed, the tower cleared him for takeoff on runway 10L and cautioned for possible wake turbulence. He stated that he then began a rolling start from the hold line on the taxiway, entered runway 10L and aligned the aircraft on the runway centerline using the electric nosewheel steering button (a glare shield or console-mounted split rocker switch, spring-loaded to center, which requires both halves of the switch to be depressed left or right to command nosewheel steering movement.) He stated: I gradually added power to come up to takeoff power. I believe that it was during the mid stage of the takeoff roll that I experienced one or two asym[m]etrical surges that caused the plane to yaw to the right. I corrected these with the electric nosewheel steering button [NOTE: the PA-60-700P normal takeoff procedure states not to use nosewheel steering during takeoff] and believed the yawing to be associated with the electric steering button. As I approached rotation speed [93 knots indicated airspeed, according to the pilot's operating handbook], there was a strong yaw to the right. I did a partial instrument scan, manifold pressure only, and saw less than a needle width variation in power setting between the two engines. I believed at that time I was having an electrical malfunction in the nosewheel steering mechanism causing it to deflect the nosewheel to the full right position. I then pulled back on the yoke to pull the nosewheel off the runway. I believe I became airborne with the plane in this attempt, as I heard the stall warning. The plane then veered sharply to the right, going off the runway. The passenger, who was sitting in the copilot's seat, reported: ...As we started down the runway the plane did not track straight following the centerline. The pilot...adjust[ed] the front tire control by a switch on the dash. This seemed to straighten our takeoff until we were nearly airborne at which time the plane veered off the runway to the right. [The pilot] attempted to take the plane up and did so to a height of 15-20 [feet] before the stall buzzer came on. We came down hitting on the bottom of the plane.... An FAA inspector who responded to the accident scene and conducted an on-site examination of the aircraft reported that he observed the right propeller blades on the aircraft wreckage in a feathered position. The pilot stated in his NTSB accident report that the inspector asked him if he had feathered the right engine, and that he replied he had not but that he had "experienced intermittent problems with the right propeller recently." Specifically, the pilot stated that on the morning of the accident, during engine runup prior to departure from Prineville for Portland, the right propeller was "much slower coming to feather than the left prop", which he stated he attributed to a belief that "the right prop might have been serviced with a different weight oil than the left hub." The pilot also stated that "during the last several months, the right prop would oscillate occasionally under high power settings associated with climb power after departure." The pilot stated that this oscillation would not occur on every flight, and did not occur on takeoff or climb on the flight from Prineville to Portland on the day of the accident. The pilot stated that "The oscillation would cause a slight r[h]ythmic yaw, particularly on climbout, and would cease when power was reduced to cruise settings." According to copies of the aircraft and engine logbooks furnished with the pilot's NTSB accident report, the aircraft's last annual inspection was on June 6, 1997. The logbook copies indicated that at the time of this annual inspection, the aircraft and both engines had 1,854.0 hours in service. Both engines had 1,891.8 hours in service as of September 18, 1997, the most recent engine logbook entries. Textron Lycoming Service Instruction 1009AK recommends an 1,800-hour time between overhauls (TBO) interval for the aircraft's Lycoming TIO-540-U2A engines. The FAA inspector, who is a certificated airframe and powerplant (A & P) mechanic, conducted a field disassembly examination of the aircraft's right engine on November 14, 1997. This examination did not reveal any evidence of a pre-impact engine mechanical problem. The right propeller from the accident aircraft (a 3-blade, constant speed, full feathering Hartzell HC-C3YR-2UF hub mated with FC7451 blades) was sent to the facilities of the propeller manufacturer, Hartzell Propeller Company Inc. of Piqua, Ohio, where a teardown examination of the propeller and a functional test of its governor were conducted under supervision of an FAA inspector from the FAA Vandalia, Ohio, Manufacturing Inspection District Office (MIDO), on July 9, 1998. Based on damage signatures observed to the propeller during the examination, and the functional test of the governor, Hartzell's conclusions from this examination were that the propeller was not feathered at impact but did rotate toward feather during the crash sequence; that the propeller was rotating and generating power; and that there were no pre-impact discrepancies that would preclude normal operation of either the propeller or the governor. According to the PA-60-700P POH, normal takeoffs in the aircraft are made with 20 degrees of flaps, with a takeoff speed of 93 knots indicated airspeed (KIAS). The POH normal takeoff procedure specifies that nosewheel steering not be used during takeoff. The aircraft's stall speed at maximum takeoff weight (6,315 pounds), flaps 20 degrees, zero thrust power, and 0 degrees bank angle is approximately 74 KIAS, and its single-engine air minimum control speed (Vmca) is 85 KIAS. The aircraft's accelerate/stop distance at sea level, temperature 12 degrees C, maximum takeoff weight, and zero wind is approximately 4,000 feet. In addition to nosewheel steering (or if nosewheel steering is not available), directional control in the PA-60-700P can be maintained on the ground by use of differential braking and differential power. The POH does not specify the airspeed at which the aircraft's rudder becomes effective during takeoff roll. Portland International runway 10L is an 8,000 by 150 foot grooved asphalt runway. The pilot reported on his NTSB accident report that the runway was dry at the time of the accident. The FAA preliminary accident report indicated that the aircraft departed the runway at midfield. A 1256 Portland weather observation reported the winds from 180 degrees at 5 knots. According to copies of the pilot's logbook, furnished by the pilot with his NTSB accident report, the pilot's last documented biennial flight review was on September 14, 1991, in an Aero Commander 690B aircraft. The pilot stated he also received a flight review on August 1, 1993, in a Cessna 340 aircraft, but "neglected to have [the instructor] sign my logbook recording the review" (the pilot's logbook was annotated "checkout" for this flight, a 1.3-hour flight from Prineville to Pullman/Moscow Regional Airport, Pullman, Washington.) The pilot stated that after a 20-month layoff from flying (from October 10, 1995, to June 9, 1997), he resumed flying with "a current pilot who is not a C.F.I., but who is a past Naval Flight Instructor who is current in numerous aircraft including Piper Malibus and Cessna Citations." The accident pilot stated that he flew with this pilot for 25.5 hours of "dual time in the Aerostar" between June 9, 1997, and July 9, 1997. The accident pilot stated that he subsequently flew with this pilot five times between August and November 1997 "to review aircraft systems and check my pilot competencies", with the most recent of these flights being November 2, 1997. A check of the FAA airman registry revealed that as of July 1998, the pilot with whom the accident pilot reported flying in the PA-60-700P held an airline transport pilot certificate with airplane single-engine land, airplane multiengine land, and glider ratings. A telephone interview with this pilot was conducted on October 27, 1998. This pilot stated he is currently a corporate contract pilot who regularly flies the Piper PA-46 aircraft, and flew the accident aircraft back from Ohio with the accident pilot in June 1997. The pilot stated he was current in the PA-60 at the time, and received his checkout in the aircraft from the previous aircraft owner. He estimated his total pilot-in-command time in make and model as 20 to 30 hours. The pilot described his role during the flights in the accident aircraft with the accident pilot as being a safety pilot, looking out for other traffic, and discussing operating techniques in the PA-60 and differences from the Cessna 340 and Aero Commander 690B (both of which the pilot had previously owned.) The pilot stated he did not do any ground time with the accident pilot, but stressed the importance of manual study to him. The pilot stated that slow speed handling was one area he recommended to the accident pilot to work on, but assessed the accident pilot's overall pilot performance as being "well within commercial [practical test standards]." The accident pilot reported the following flight times: 2,615 hours total, including 1,931 airplane multiengine and 67 in make and model; 2,480 hours pilot-in-command (PIC) including 2,000 hours airplane multiengine PIC and 41 hours PIC in make and model; 65 hours in the last 90 days; 8 hours in the last 30 days; and 0.8 hours in the last 24 hours. The pilot reported that all of his flight time in the past 90 days was in the PA-60.

Probable Cause and Findings

The pilot's selection of an improper remedial action for an unanticipated yaw excursion during takeoff roll, resulting in the aircraft becoming airborne with inadequate airspeed and consequent loss of aircraft control.

 

Source: NTSB Aviation Accident Database

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