SEA04FA022

At 0347, the pilot received a standard weather briefing, which indicated instrument flight rules would prevail along the entire route of flight. The pilot was advised of an advisory for mountains to be obscured, an Airmet for occasional moderate turbulence below 15,000 feet msl, icing, occasional moderate rime or mixed in clouds and precipitation, with a freezing level to 16,000 feet msl. At 0540, radar contact was established with the flight. At 0635, while at 11,000 feet msl the pilot requested a higher altitude, and at 0639 the pilot reported that he was at 13,000 feet msl and clear of rime ice. At a time which could not be determined the pilot advised air traffic control that he had just lost his suction gage, and shortly thereafter radioed, "Mayday, Mayday, Mayday." At 0650:52, the airplane was on a south-southwesterly heading at 13,100 feet msl, and at 0650:59 it was at 12,900 feet msl on a southeasterly heading. From 0651:04 until 0651:28 the airplane was between 12,800 feet msl and 13,100 feet msl turning left from a south-southeasterly heading to an east-southeasterly heading. Between 0651:28 and 0651:52 the airplane descended on a northeasterly heading to an altitute of 10,700 feet. The airplane then made a right turn of approximately 60 degrees to a south-southeastly heading, and seven seconds later at 0651:59 was observed at 10,500 feet msl, indicating its descent had been arrested. Six seconds later, at 0652:05, the flight had descended to an altitude of 6,800 feet msl on the same heading. The last radar hit was at 0652:17 when the airplane was on a northwest heading at 6,400 feet msl. The engine and fuselage were located 1 mile northwest of Warren, Oregon, while both wings, the tail section and the left stabilizer were located approximately 1 mile northwest of the main wreckage. Separation signatures were consistent with the left stabilizer separating in an upward and aft direction, while both wings had separated in an upward and positive direction. Examination of the vacuum pump and its history indicates that it is probable that the pump failed due to vane failure as a result of highly worn vanes being subjected to impact bending loads from the uneven interior surface of the housing, with a possible contribution from contaminating material between the vanes and the housing.

History of flight

On November 25, 2003, approximately 0653 Pacific standard time, a Beech S35, N10BX, was destroyed after impacting terrain following an in-flight breakup and uncontrolled descent from cruise flight near Warren, Oregon. The instrument rated commercial pilot and his three passengers received fatal injuries. Visual meteorological conditions prevailed at the accident site, but instrument meteorological conditions were reported over the pilot's route of flight. An instrument flight rules (IFR) flight plan had been filed for the personal cross-country flight being conducted under 14 CFR Part 91. The flight originated from the Arlington Municipal Airport (AWO), Arlington, Washington, at approximately 0535, and was en route to Medford (MFR), Oregon.

Approximately two hours prior to the flight the pilot had received a standard weather briefing from the Seattle Automated Flight Service Station (AFSS). At 0524, (all times are referenced to Pacific standard time) the pilot contacted the AFSS stating that he was on the ground at AWO, had filed an IFR flight plan to MFR, and that he was about ten minutes late. The specialist told the pilot to hold while he proceeded to coordinate the clearance with the Seattle Air Route Traffic Control Center (ARTCC). At 0527 the specialist cleared N10BX to the WATON NDB (non directional beacon), climb and maintain four thousand. The pilot read back the clearance, which the specialist confirmed was correct, and the conversation ended at 0528.

At 0540, radar contact was established with N10BX at an altitude of 1,400 feet mean sea level (msl), and at 0543 radar indicated the airplane was at 3,700 feet msl. At 0635, while at 11,000 feet msl, N10BX requested a higher altitude; ARTCC cleared the pilot to 13,000 feet msl. Radar data indicated that at 0639 N10BX was at 13,000 feet msl, and at an unknown time the pilot reported that he was at 13,000 feet and "clear of rime ice." The pilot subsequently radioed to ARTCC, at an undetermined time, "ah, we just lost our suction gage," the controller responding "...climb and maintain 15 thousand? You requesting a higher altitude? Is that what you said?" The pilot then replied, "Mayday, Mayday, Mayday." There were no further transmissions from N10BX.

Radar data revealed that at 0650:52 N10BX was at 13,100 feet msl beginning a right turn from a southerly heading to a south-southwesterly heading, and seven seconds later at 0650:59 was at 12,900 feet msl beginning a right turn to a southeasterly heading. At 0651:04 N10BX was at 12,800 feet msl starting a right turn from the southeast to south-southeast, and at 0651:11 the flight was still at 12,800 feet msl, but then made a left turn back to a heading of southeast. At 0651:16 the aircraft had ascended to 12,900 feet msl and was making a turn further left to a east-southeasterly heading, reaching 13,100 feet msl at 0651:28. Radar data indicates that at 0651:28 the airplane's heading changed from east-southeast to a heading of northeast, having descended to an altitude of 10,700 feet msl by 0651:52. The airplane then turned back to a heading of east-southeast and descended to an altitude of 10,500 feet msl at 0651:59. N10BX continued on a heading of east until 0652:05, when its altitude was recorded at 6,800 feet msl. It then proceeded on a northwesterly heading until 0652:17, when the last radar hit recorded the aircraft at an altitude of 6,400 feet msl.

The fuselage and engine were located on the east side of Scappoose Bay, approximately 3 nautical miles north-northeast of the Scappoose Industrial Airpark, Scappoose, Oregon, and approximately 1 nautical mile northeast of Warren, Oregon, having impacted a low-lying marsh area. The fuselage came to rest in an inverted position oriented on a magnetic heading of 350 degrees. There was no evidence of fire. Both wings, the tail section, and the left stabilizer of the airplane were located approximately 1 nautical mile northeast of where the fuselage and engine came to rest.

The recovery of the wreckage was delayed due to the varying tides inherent to the region, with high tide estimated at 1 1/2 feet of water at the accident site. Recovery efforts commenced on November 26, 2003, and concluded on December 3, 2004. The wreckage was transported to a secured storage facility in Independence, Oregon, to await further examination by representatives of the National Transportation Safety Board and the Federal Aviation Administration.

Personnel information

A review of Federal Aviation Administration (FAA) records revealed that the pilot was an instrument-rated commercial pilot in airplane single and multiengine land aircraft. FAA records also revealed the pilot held an aircraft airframe and powerplant certificate. The pilot possessed a second class medical certificate, dated March 19, 2002, without limitations. On the application for the medical certificate, the pilot reported his total pilot time as 2,867 hours, with 4 hours flight time in the last 6 months.

According to the pilot's flight log, the last entry was on August 30, 2003. A .5 hour local flight with one instrument approach was entered, but no actual or simulated instrument flight time was logged. The pilot's last recorded flight that included actual instrument flight time was on August 23, 2003, which was a 3.6 hour cross-country flight that included a segment of 1.2 hours of actual instrument flight time. At this time the pilot's total flight time was recorded to be 2,235.4 hours in single-engine aircraft, and 1028.1 hour in multiengine airplanes. The pilot's most recent biennial flight review was conducted on December 31, 2002.

Aircraft information

N10BX, (S/N D-7876), a model S35, was manufactured by the Beech Aircraft Corporation in 1965. The airplane was equipped with a Teledyne Continental IO-520 fuel injected engine rated at 285 horsepower, and a McCauley 2-blade, all metal, constant-speed propeller.

According to aircraft maintenance records, the pilot, a certificated airframe and powerplant mechanic, conducted the most recent annual inspection, which was performed on June 12, 2003, at a tachometer time of 3,365 hours and a total airframe time of 7,552.5 hours. The most recent inspection of the aircraft's transponder, altimeter, pressure altitude reporting system, and alternate static system was checked satisfactorily on October 30, 2002. A serviceable vacuum pump, (S/N 22C-219) was installed on November 21, 2001.

Meteorological information

At 0347 the pilot contacted the AFSS stating that he would be departing at 0500 from the AWO, IFR to MFR at 10,000 feet. The pilot then gave the briefer his call sign and requested a standard weather briefing. The briefing specialist advised the pilot of an advisory for mountains to be obscured, an Airmet for occasional moderate turbulence below 15,000 feet, icing, occasional moderate rime or mixed in clouds and precipitation, with a freezing level to 16,000 feet. The specialist advised the pilot of a frontal system off shore pushing clouds and precipitation into most of the pacific northwest, and that radar indicated precipitation "...all the way down to about Salem. The specialist then informed the pilot that the weather at MFR was wind calm, visibility 3 statute miles, "bouncing around" between 3/4 and 3 statute miles, with the RVR (runway visual range) for runway 14 4,500 feet, variable to 6,000 feet with mist. The ceiling was 7,000 overcast with the temperature and dew point both minus 1 degree. The specialist went on to say that along the route of flight there was widespread rain down to Salem with multiple layers of clouds. The briefer continued by advising the pilot that the area forecast for western Washington was broken clouds at 2,000 feet, overcast clouds at 4,000 feet, with tops at 20,000 feet and visibilities 3 to 5 miles in rain or mist, and snow or mist above 2,000, and southerl