N966MA

HISTORY OF FLIGHT

On March 11, 2004, at 2035 Pacific standard time, a Mitsubishi MU-2B-40, N966MA, crashed into the Napa River under unknown circumstances, while on approach to the Napa County Airport (APC), Napa, California. The pilot/owner was operating the airplane under the provisions of 14 CFR Part 91. The airplane was destroyed. The private pilot and one passenger were fatally injured. Visual meteorological conditions prevailed for the cross-country flight that departed the Imperial County Airport (IPL), Imperial, California, at an undetermined time. An instrument flight rules (IFR) flight plan had been filed.

The Federal Aviation Administration (FAA) issued a family concerned alert notice (ALNOT) on March 15, 2004, after the pilot had not contacted family members to inform them that he had returned. Local officials and the Civil Air Patrol initiated a search on March 16, 2004, in the Napa River area. They located the airplane on March 18, 2004, in the Napa River, 3 miles south of APC.

The FAA provided a summary of recorded radio transmissions, which indicated that the pilot checked in on Oakland Air Route Traffic Control Center (ARTCC) Center sector R41 frequency. At 2030, he reported leaving 6,000 feet; he also stated that he had the information for Napa Airport, and had it in sight. The controller cleared him for the approach. He advised the controller that he would like to cancel his IFR, and switch to traffic advisory frequency. At 2032, the controller cleared him to squawk 1200, and switch to advisory frequency.

A Safety Board specialist plotted recorded radar data. The target with the airplane's discreet beacon code maintained a westerly heading. At 2032, the target was southeast of Napa. The code changed to 1200, and the target continued in a westerly direction south of Napa. At 2035, the target crossed the Napa River, and began a left turn away from the airport. The target completed about 90 degrees of turn, and the last target was on the west side of the river near the accident site, which was in the river.

PERSONNEL INFORMATION

A review of FAA airman records revealed that the pilot held a private pilot certificate with ratings for airplane single engine land, multiengine land, and instrument.

The pilot held a second-class medical certificate issued on January 22, 2004. It had the limitations that the pilot must wear lenses for distant vision, and possess glasses for near vision. On his medical application, the pilot reported a total time of 4,500 total flight hours, with 100 hours flown in the past 6 months.

An examination of the pilot's logbook indicated a total flight time of 4,545.7 hours as of December 31, 2003, with 1,651.2 hours of MU-2 total flight time. The Safety Board investigator-in-charge (IIC) was not provided with a pilot logbook for the year 2004.

According to the pilot's logbook, he had regularly participated in flight training from Flight Safety International, Honeywell International, Inc., and Mitsubishi since he had purchased the airplane in September 1997.

AIRCRAFT INFORMATION

The airplane was a Mitsubishi MU-2B-40, serial number 405SA. A review of the maintenance records provided by Crownair Aviation indicated a total airframe time of 4,119 hours at the last 100-hour inspection on January 14, 2004. The records indicated completion of 100-hour, 500-hour, 1,000-hour/3-year, and 2,000-hour periodic inspections in accordance with the Mitsubishi Inspection Program on June 4, 2003.

The left engine was with a Honeywell TPE331-10-511M, serial number P-36063C. Total time on the engine at the last 100-hour inspection was 4,119 hours with 585 hours since overhaul. The left propeller had 409 hours since overhaul at the last 100-hour inspection.

The right engine was with a Honeywell TPE331-10-511M, serial number P-36064C. Total time on the engine at the last 100-hour inspection was 4,119 hours with 585 hours since overhaul. The right propeller had 409 hours since overhaul at the last 100-hour inspection.

METEOROLOGICAL INFORMATION

The closest official weather observation station was Napa, which was 3 nautical miles (nm) southwest of the accident site. The elevation of the weather observation station was 35 feet msl. An aviation routine weather report (METAR) was issued at 1954 with the following information: skies clear; visibility 10 miles; winds calm; temperature 59 degrees Fahrenheit; dew point 45 degrees Fahrenheit; altimeter 29.93 inHg.

WRECKAGE AND IMPACT INFORMATION

San Mateo County Sheriff's Boat Patrol found the airplane on March 18, 2004, in 20 feet of water with the use of their side-scan sonar. The Safety Board IIC, and a representative from Mitsubishi Heavy Industries America, Inc., a party to the investigation, responded to the accident site on March 20, 2004, for the recovery of the airplane from the Napa River.

The right wing and engine with propeller assembly separated from the fuselage, and was recovered with the airframe. All of the four propeller blades showed evidence of rotational damage with S-bending and leading and trailing edge gouging.

The right engine was recovered on March 20, 2004. The left engine was recovered on April 16, 2004. The left tip tank had been recovered by local area fisherman at the mouth of the Napa River a few days after the accident, and given to the FAA.

MEDICAL AND PATHOLOGICAL INFORMATION

The Napa County Coroner conducted an autopsy on the pilot on March 12, 2004. The FAA Bioaeronautical Sciences Research Laboratory, Oklahoma City, Oklahoma, performed a toxicological analysis from samples obtained during the autopsy. The results of the analysis of the specimens contained no findings for carbon monoxide, cyanide, and tested drugs.

The report contained the following results for tested volatiles:

31 (mg/dL, mg/hg) Ethanol detected in blood

48 (mg/dL, mg/hg) Ethanol detected in urine

57 (mg/dL, mg/hg) Ethanol detected in brain

49 (mg/dL, mg/hg) Ethanol detected in muscle

10 (mg/dL, mg/hg) Acetaldehyde detected in blood

1 (mg/dL, mg/hg) Acetaldehyde detected in urine

2 (mg/dL, mg/hg) Isopropanol detected in blood

1 (mg/dL, mg/hg) Isopropanol detected I urine

34 (mg/dL, mg/hg) Isopropanol detected in muscle

39 (mg/dL, mg/hg) N-Butanol detected in blood

23 (mg/dL, mg/hg) N-Butanol detected in urine

8 (mg/dL, mg/hg) N-Butanol detected in brain

46 (mg/dL, mg/hg) N-Butanol detected in muscle

3 (mg/dL, mg/hg) N-Propanol detected in blood

3 (mg/dL, mg/hg) N-Propanol detected in urine

2 (mg/dL, mg/hg) N-Propanol detected in brain

4 (mg/dL, mg/hg) N-Propanol detected in muscle

A clinical section also indicated a finding of 0.08 (pmol/nmol) serotonin metabolite ratio detected in urine.

A note was included in the toxicological report that stated that the ethanol found in this case was from postmortem ethanol formation and not from the ingestion of ethanol.

TESTS AND RESEARCH

Investigators examined the wreckage at Plain Parts, Sacramento, California, on May 4-5, 2004.

AIRFRAME

Examination of the wreckage indicated that the landing gear were down. The flaps were at 20 degrees (both selector and physically). The retriever cut the control cables, but the control cables remained attached to their respective bellcranks. Investigators established control continuity by matching the cut ends.

The left engine cockpit control was at the emergency stop position. The right engine was at the taxi position. Both generator switches were on.

The left main fuel selector valve broke, and the body was open (up). The right main fuel selector valve off lever was intact with two witness marks. One mark was in the OFF position; the other was in the ON position. Both wing valves were in the OFF position. The Mitsubishi investigator indicated that this was due to the deformation the structure experienced during the accident sequence.

ENGINES

Honeywell personnel examined the engines under the supervision of the IIC at their facility in Phoenix, Arizona, on June 15-17, 2005. They submitted a written report, and pertinent findings in the following section.

Fuel Pumps

The fuel pump from the left engine was functionally tested on June 17, 2004. Fuel flow for the left pump tested below the minimum discharge fuel rate for test points 3 and 8. Test point 3 represents the equivalent fuel pump speed at an engine speed of 100 percent. Maximum fuel flow requirements of the engine at 100 percent speed range from 500 to 600 lb/hr. Since the discharge fuel flow (1080 lb/hr) was roughly twice that required by the engine, pump operation 17 percent below the test instruction specification would not negatively impact engine operation (i.e., the fuel pump is designed with excess capacity). Test point 8 represents an engine start/acceleration fuel flow, and does not impact the in-flight operation of the engine. Technicians disassembled both fuel pumps after the functional testing. Carbon bushings, which support the high-pressure pump, were fractured in both the left and right engine pumps due to impact damage. The remaining components of the fuel pumps were intact.

Investigators did not functionally test the fuel pump from the right engine due to housing damage. The housing on the right engine pump was cracked, and leaked fuel when pressurized.

Fuel Controls

Fuel controls from both engines were examined on August 25-26, 2004, at the Woodward Governor Company, Rockton, Illinois. Both fuel controls were corroded and contaminated with sand and river silt. The degree of corrosion and contamination resulted in fuel controls that were largely unresponsive to inputs. No evidence of a pre-incident condition was identified in either control.

Propeller Governors

Propeller governors from both engines were examined on August 25-26, 2004, at the Woodward Governor Company. Both governors contained sand and river silt that either prevented rotation of the drive shaft or caused the drive shaft to rotate wit...