Saturday, January 21, 2006

Accident of the Week

This week's Accident of the Week involves the crash of a TwinCo just 400' short of the runway threshold. Your guess is as good as the IFR Pilot's about what happened here, so very, very close to landing.

NTSB Identification: LAX06FA089
14 CFR Part 91: General Aviation
Accident occurred Friday, January 13, 2006 in Visalia, CA
Aircraft: Piper PA-30, registration: N791Y
Injuries: 4 Fatal.

This is preliminary information, subject to change, and may contain errors. Any errors in this report will be corrected when the final report has been completed.

On January 13, 2006, about 1819 Pacific standard time, a Piper PA-30 (Twin Comanche), N791Y, impacted terrain approximately 400 feet from the approach end of runway 30 at Visalia Municipal Airport, Visalia, California. The commercial pilot was the registered owner of the airplane and operated it under the provisions of 14 CFR Part 91. The pilot and three passengers sustained fatal injuries; the airplane was destroyed. Visual meteorological conditions prevailed and no flight plan was filed. The airplane was landing following a flight from Byron Airport, Byron, California, where the pilot had picked up two passengers.

The airplane was reported overdue to the airport manager at 2145 on January 13. He received information that the airplane's services were terminated by Fresno Approach Control at 1811, approximately 7 miles north of Visalia. The airport manager checked the emergency frequency for the transmission of an emergency locator transmitter (ELT) but no aural alarm was heard. He then began a ground search for the airplane and it was located near the approach end of runway 30 at 2215.

A witness who was driving on a road paralleling the airport reported seeing the airplane at a low altitude approaching the airport. He could hear the engine running but as the airplane twisted downward and to the left, the noise stopped.

A pilot that was flying a King Air from Santa Monica Airport heard the accident pilot on the Visalia airport UNICOM. The accident pilot called downwind and the pilot and accident pilot exchanged general light conversation. The accident pilot then called base and no further transmissions were heard. The witness landed about 1830, and thought the transmissions with the accident pilot occurred between 1820 and 1825. The witness thought that there may have been another airplane on the frequency but he was not certain. After refueling, the witness departed about 1900 and returned about 2215. The pilot flew over the accident site twice during the evening and did not see the wreckage. The pilot further noted that although he did not personally know the accident pilot, the accident pilot normally flew at least three to four times per week for business purposes. The weather conditions were described as beautiful. Dark lighting conditions existed and there were light winds favoring runway 30, with clear skies or high cirrus clouds. The pilot also noted that the medium intensity approach lighting system was on when the accident airplane was attempting to land.

On January 14, the National Transportation Safety Board investigator, two Federal Aviation Administration inspectors from the Fresno, California, Flight Standards District Office, and a representative from the New Piper Aircraft, a party to the investigation, responded to the accident scene. The airplane came to rest on a heading of 060, 410 feet from the touchdown area of runway 30 and just left of the runway centerline.

The wreckage was confined to the general impact area and all control surfaces were accounted for and still attached to the airplane. Vertical aft accordion crushing was evident on the forward engine nacelles and the nose section. The entire forward portion of the fuselage was crushed and pushed aft. The right wing sustained leading edge crush inboard of the right engine in both an upward and aft direction and the light buckling was present over the wing skins. The left wing leading edge was crushed upward and aft from the left engine, outboard 4.5 feet, to a rivet line where the skin was torn. From this point outboard, the leading edge was bent upward and crumpled. The empennage section was circumferentially buckled 3 feet forward of the vertical stabilizer. The flaps appeared symmetrically extended. The landing gear jack screw indicated zero threads, which was consistent with the landing gear extended. A blue tinted fuel consistent in smell with 100 LL was found in each of the main and outboard fuel tanks.

The right propeller was located approximately 3 feet from the right wing tip and buried in soil. Investigators noted that one of the blades displayed a mild aft bending the length of the blade and the leading edge was polished. The other blade had light, chordwise scratching but was otherwise unremarkable. The left propeller was examined, still attached by two flange bolts to the left engine. One blade had chordwise scratches, with leading edge polishing. This blade had mild aft bending about mid-blade. The other left propeller blade had a gouge out of its tip and had mild aft bending mid-blade.

The ELT was removed from its mount in the tail section of the airplane. Investigators noted that the switch was in the "ARM" position and that the housing cover was cracked. The switch was moved to the "ON" position and investigators noted an aural alarm over frequency 121.5. After changing the switch back to the "ARM" position, investigators attempted to activate the unit but no aural alarm was heard.
One idea that emerges from this discussion is the wisdom of flying a high, tight, close-in approach. Some pilots and CFIs favor this, under the notion that keeping the plane high and close until landing is assured, and then basically diving for the runway, could prevent accidents just such as this one. The IFR Pilot hasn't adopted this as his standard operating procedure, preferring instead to fly a standard pattern.

CFIs out there, if you favor this approach, would you do so even in a twin?

1 comment:

Dr. Van Skleeve said...

I believe standard, stabilized downwinds and approaches make for the safest and best landings, whether in singles or twins.

Perhaps this accident was caused by flying a non-standard approach compouded by a stall on base/final or a "diving final" coupled with some type of spatial disorientation.

Was there definative evidence of any type of engine failure? Looks like they had fuel onboard too.