Willow, AK, USA
N4588C
Cessna 170B
The private certificated pilot was returning from a round-robin VFR personal flight with three passengers. The flight was paralleling a rural highway, and was observed by a witness about 30 feet above the trees, southbound on the west side of the highway. The nose of the airplane appeared "slightly up." It then made a smooth right turn, about 180 degrees toward the north, nosed down about 45 degrees, and descended from view into the trees. Another witness reported that she observed the airplane northbound at a low altitude on the west side of the highway. The airplane appeared to be making a right banking turn, and then nosed down toward the trees. The airplane began a 3/4 spiral turn downward and disappeared into the trees. An on-site investigation disclosed that the airplane collided with several trees, and then struck soft ground in about a 45 degree nose down attitude. The cabin floor was oriented about 45 degrees to the right. Numerous broken tree limbs were observed about 50 feet above the impact site. The empennage was separated from the main fuselage about the forward attach point of the vertical stabilizer, and was located about 20 feet north of the main impact site. An examination of the engine revealed no evidence of any preimpact mechanical malfunctions.
HISTORY OF FLIGHT On July 16, 2004, about 2145 Alaska daylight time, a tundra tire-equipped Cessna 170B airplane, N4588C, was destroyed when it collided with trees and the ground following a loss of control while maneuvering, about 12 miles north-northwest of Willow, Alaska. The airplane was being operated as a visual flight rules (VFR) cross-country personal flight under Title 14, CFR Part 91, when the accident occurred. The airplane was operated by the pilot. The private certificated pilot, and the three passengers, received fatal injuries. Visual meteorological conditions prevailed, and a round-robin VFR flight plan was filed from Merrill Field, Anchorage, Alaska, to Talkeetna, Alaska. The accident flight originated at the Talkeetna Airport at 2119 for the return portion of the flight to Anchorage. At 1704, the pilot telephoned the Federal Aviation Administration's (FAA) Kenai Automated Flight Service Station (AFSS) to inquire about the weather conditions from Merrill Field to Talkeetna. The flight service station specialist stated, in part: "Okay, no AIRMETS; Merrill's clear and ten [miles visibility], wind 280 [degrees] at nine [knots]. Talkeetna's few [clouds] at 10,000 feet, ten miles [visibility], winds variable at five [knots]." The pilot then filed a VFR flight plan that included a departure time of 1800, with a route from Merrill Field, to Hatcher Pass, Alaska, to Talkeetna. The pilot indicated that the return route would be Talkeetna, to Big Lake, Alaska, to Merrill Field. The total time en route was planned as 6 hours, to include ground time in Talkeetna, with 5 hours of fuel aboard. At 1809, the pilot contacted the Kenai AFSS via radio and opened his flight plan. The flight landed at Talkeetna at 1912. The pilot contacted the Talkeetna FSS at 2119 to report his departure. About 2146, the Alaska State Trooper's dispatch center received a telephone call from a witness who reported the accident at mile 84 of State Highway 3. The witness said she was driving on a motorcycle, northbound on Highway 3, and observed the airplane about 30 feet above the trees, southbound on the west side of the highway, paralleling the highway. The nose of the airplane appeared "slightly up." It then made a smooth right turn, about 180 degrees toward the north, and then nosed down about 45 degrees, and descended from view into the trees. Another witness reported that she was also northbound on Highway 3. She saw the airplane northbound at a low altitude on the west side of the highway. The airplane appeared to be making a right banking turn, and then nosed down toward the trees. The airplane began a 3/4 spiral turn downward, and disappeared into the trees. Other passing motorists stopped to look for the airplane, but were unable to locate the crash site. A third witness reported that she was camping along a creek, near the accident site. She indicated that she did not see the airplane, but heard a loud crashing sound. The accident site was not located from the ground until a helicopter was called to the area by the Alaska State Troopers. The crash site was located in an area of trees, about 235 feet west of the highway. PERSONNEL INFORMATION The pilot held a private pilot certificate with an airplane single-engine land rating. The most recent third-class medical certificate was issued to the pilot on June 24, 2003, and contained the limitation that the pilot must wear corrective lenses for distant vision. An examination of the pilot's logbook revealed that he began pilot training in October, 1986, and accrued 7.0 hours of flight instruction. He accrued 3.1 hours of instruction in March, 1987, and then began continuous training in June, 1987, until receiving his private pilot's certificate on June 27, 1987, with 53.5 hours. The pilot did not receive any night instruction, but accrued an additional 2 hours in a tailwheel airplane in 1987. He accrued 10.8 additional tailwheel hours in 1988. In 1989, 1990, and 1991, the pilot accrued 12.3 tailwheel hours (no instruction noted), 2.0 hours of single-engine land dual instruction, 7.1 hours of single-engine sea dual instruction, and 1.1 hours of complex single-engine land dual instruction. No further logbook entries were noted until July, 2003, when the pilot began flying the accident airplane. He received 11.7 hours of dual instruction, including 3.1 hours at night. He completed his night flying requirements, and received a night endorsement on August 28, 2003. The last entry in the pilot's logbook is July 5, 2004, at which time his total experience was 151.9 hours. Examination of the "remarks and other endorsements" page in the pilot's logbook revealed endorsements for solo, cross country, night, and a biennial flight review (BFR) on August 29, 2003. AIRCRAFT INFORMATION The airplane had accumulated a total time in service of 5,327.73 hours. Examination of the maintenance records revealed that the most recent annual inspection of the engine and airframe was accomplished on September 27, 2003, 184.91 hours before the accident. The engine, a Continental C-145-2, had accrued a total time in service of 5,197.83 hours. The maintenance records note that the engine was was overhauled by a certified repair station on February 2, 2004. The overhaul included the replacement of the engine's crankshaft with one that had an ARP502 Type 1 propeller flange. It was reinstalled on the airplane without a propeller, 592.93 hours before the accident. The overhaul, documented on a FAA Major Repair and Alteration document (FAA FORM 337) on February 10, 2004, was approved by an FAA airworthiness inspector. The Form 337 also noted that the engine was converted to an 0-300-D configuration. The engine retained the original accessory case, and the original engine serial number. On February 11, 2004, under Supplemental Type Certificate (STC) SA7441SW, a McCauley 1A175-SFC propeller was installed, documented by FAA Form 337, and approved by an FAA airworthiness inspector. METEOROLOGICAL INFORMATION The closest official weather observation station is Talkeetna, Alaska, which is located 23 nautical miles north-northwest of the accident site. At 2153, an Aviation Routine Weather Report (METAR) was reporting in part: Wind, 180 degrees (true) at 5 knots; visibility, 10 statute miles; clouds and sky condition, 10,000 feet scattered; temperature, 72 degrees F; dew point, 54 degrees F; altimeter, 29.87 inHg. COMMUNICATIONS A transcript of the air to ground communications between the airplane and all involved FAA ATC facilities is included in the public docket of this accident. WRECKAGE AND IMPACT INFORMATION The National Transportation Safety Board investigator-in-charge (IIC) and an FAA inspector, Anchorage Flight Standards District Office (FSDO), examined the airplane wreckage at the accident site on July 17, 2004. The examination revealed that the airplane collided with several trees, and then struck soft ground in about a 45 degree nose down attitude, with about a 45 degree right bank. All of the airplane's major components were found at the main wreckage area, and the wreckage was confined to about an 80 foot radius. Numerous broken tree limbs were observed about 50 feet above the impact site. The empennage was separated from the main fuselage near the forward attach point of the vertical stabilizer, and located with the tailwheel up, about 20 feet north of the main impact site. The point of separation had buckling compression, and tearing of the metal structure. The leading edge of the left horizontal stabilizer was undamaged. The outboard end of the left elevator was undamaged, but the trailing edge had upward spanwise bending to about mid-chord. The right elevator had upward spanwise bending, to about mid chord, with downward and aft bending of the outboard end. The top of the vertical stabilizer had minor buckling and denting. The rudder had a left bend along its vertical span, with no damage to the top of the rudder. At the rear door post, rescue personnel had cut the upper cabin structure loose and peeled it forward. The aft segment of fuselage structure from the rear door post to the point of empennage separation, was peeled aft. The right wing was lying flat on the ground, displaced aft from the cabin about 45 degrees. The right wing had 45 degree aft crushing of the leading edge along a flat, vertical plane, beginning about the inboard end of the aileron attach point. The crush line angled aft to the trailing end of the wingtip, exposing the outboard end of the spar. The inboard leading edge of the wing had minor spanwise denting. The outboard end of the aileron had inward buckling and bending about midspan of the aileron. The flap was attached to the wing and had upward and inward curling of the inboard trailing end, adjacent to the main cabin structure. The left wing was lying inverted, forward of the main cabin, on about a 45 degree angle, and was torn from its respective attach points. The left wing had extensive leading edge aft crushing and downward curling, more to the underside of the wing. This was evident from the leading edge landing light assembly, outboard to the tip. The inboard leading edge had aft vertical crushing to the spar, with slight downward curling. The leading edge had aft semicircular crushing between the lift strut attach point and left wing landing light assembly. The left aileron remained attached to the wing. The left flap remained attached to the wing. The right main landing gear strut was attached to the fuselage and buried in the ground. The right main wheel and tire was separated from the lower end of the strut, and located about 25 feet north of the empennage point of rest. The left main landing gear strut with its wheel and tire, remained attached to the fuselage. Due to the impact damage, the flight controls could not be moved by their respective control mechanisms. The continuity of the flight control cables was established to the cabin/cockpit area. The cockpit area had extensive inward and upward crushing on about a 45 degree angle, from the forward, lower right corner of the firewall. The instrument panel had extensive buckling, and forward "U" shaped bending at the lower edge of the panel that corresponded to the forward seat positions. Both flight control yokes were bent to the right. The mixture control was forward. The throttle appeared to be out, or aft, and bent downward and to the right. The fuselage structure, from the rear door post to the point of separation of the empennage, had extensive distortion, and upward crushing and tearing of the lower belly area. The propeller assembly was buried in the ground, under the engine. The tip of one propeller blade was visible above the surface. Excavation of the engine revealed that the one visible propeller blade was straight. The other propeller blade was curled aft against the right side of the engine. The entire propeller was angled about 45 degrees from its normal plane of rotation. The exhaust tubing did not display any extensive crushing. The right side flange of one exhaust tube was fractured. The carburetor was broken from its engine mounting pad. The throttle butterfly valve was nearly closed. The mixture control at the carburetor was rich. On July 28, 2004, an engine examination was conducted at B J Custom Engines, Palmer, Alaska. The parties noted in this report participated in the examination. The examination revealed that the engine crankshaft flange was circumferentially fractured at the inner edge of the flange, and displaced about 45 degrees. The magnetos were placed on a test bench and produced spark from each tower. The massive center electrode sparks plugs 1, 2, 4, and 6, were dry and gray. Plugs 3 and 5 were slightly damp with oil. The carburetor contained no fuel. The fuel inlet screen was free of contaminants. The accelerator pump, jet, and venturi were undamaged. One of the metal floats had slight inward buckling of the assembly along the outside face of its structure. No preaccident or preimpact mechanical malfunctions were discovered. MEDICAL AND PATHOLOGICAL INFORMATION A postmortem examination of the pilot was conducted under the authority of the Alaska State Medical Examiner, 4500 South Boniface Parkway, Anchorage, Alaska, on July 19, 2004. The examination revealed that the cause of death for the pilot was attributed to blunt force injuries. A toxicological examination was conducted by the FAA's Civil Aeromedical Institute (CAMI) on August 24, 2004. The examination was negative for any alcohol or drugs. ADDITIONAL INFORMATION The Safety Board released the wreckage, located at Wasilla, Alaska, to the owner's representatives on December 6, 2004. No parts or components were retained by the Safety Board.
The pilot's failure to maintain adequate airspeed, which resulted in an inadvertent stall while maneuvering, and a collision with trees and terrain during an uncontrolled descent.
Source: NTSB Aviation Accident Database
Aviation Accidents App
In-Depth Access to Aviation Accident Reports
