CEN11FA559

NTSB accident investigation · Cessna 182C · Boulder, CO · August 9, 2011

Accident · Minor injuriesField investigationFinal report
Date
August 9, 2011, 17:14 local (23:14 UTC)
Place
Boulder, CO
Injuries
1 minor
Damage
Substantial damage
Phase of flight
Approach
Aircraft
N8717TCessna 182C
Defining event
Approach: Loss of engine power (total)
Weather
Visual (VMC) · Day
Status
Completed · report September 15, 2014
Report
Approved by Office Director
NTSB office
Central Region
Parties
Flight Standards District Office - FAA
FAA report
20110809030209A
Case key
81441

From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the accident.

On this page

Probable cause

The malfunction of the throttle linkage to the induction air box, which resulted in a loss of engine power and subsequent forced landing.

Findings · 1

NTSB’s coded findings. Those marked are part of the probable cause; the rest are factors or other findings. Under each, the cases with the same finding.

Engine controlsAircraft › Aircraft power plant · MalfunctionCessna 182C: 1 caseAll aircraft: 51 casesProbable cause

Sequence of events

The events NTSB coded, in order, by phase of flight. The defining event is the one that best describes the accident. Under each, the cases with the same event anywhere in their sequence.

Analysis

After two parachutists jumped from the airplane, the pilot began a descent and applied carburetor heat. The pilot reduced power for a straight-in approach while the airplane was passing through 9,000 feet mean sea level and about 3 miles from the destination airport. She then attempted to add power to adjust the descent rate, but the engine did not respond. The pilot then fully reduced the engine power then tried to advance the throttle with no response. After performing the power loss checklist, she continued toward the runway but, after encountering a downdraft, she chose to conduct a forced landing to an open field. Upon touchdown, the airplane collided with trees at the edge of the field. The propeller assembly was found attached to the engine hub, and both blades were straight with little damage consistent with them not being powered at the time of impact. About 5 gallons of fuel were drained from the left fuel tank and about 0.5 gallon was drained from the right fuel tank. The fuel selector was found in the "both" position. Because of the fuel leakage due to impact damage, it was not possible to determine exactly how much fuel was onboard at the time of the accident; however, enough fuel was present in the lines to determine that fuel starvation did not occur. No evidence of debris, obstructions, or water contamination was identified in the fuel gascolator. About 8.5 quarts of oil were found in the engine. Some oil residue was found on the belly skin of the airplane and was identified to have originated from an aftermarket oil drain installation. The front underside of the airframe was damaged and pushed upward underneath the engine compartment near the air induction box. When moved by hand, the throttle linkage to the air induction box did not move smoothly and was stiff. The throttle linkage to the induction box was adjusted, and the engine was test run while still in the airframe mounts. It started normally and ran at various power settings with no anomalies noted. Throughout the engine test run, the engine accelerated normally. A magneto rpm drop check was normal. The damage underneath the engine compartment near the box precluded a determination of whether the throttle linkage anomaly was present before impact. However, given that the engine ran normally after the throttle linkage adjustment, it is likely that the throttle linkage anomaly did occur before impact and contributed to the loss of engine power.

Factual narrative

The wreckage was released to its owner after the engine examination. The 1960 model Cessna 182C had 3,853.3 total airframe time as of its last annual inspection that was completed on July 28, 2011. The engine, a Continental Motors O-470, had 1,347.3 hours since its last overhaul. The operator provided maintenance logbooks, and upon review, no abnormalities were discovered other than routine maintenance entries and annual inspection notations. On August 9, 2011, about 1714 mountain daylight time, a Cessna 182, N8718T, landed in a field while on approach to Boulder Municipal Airport (KBDL). The aircraft was substantially damaged and came to rest after striking a tree on the north side of the field. The commercial pilot, who was the only occupant, sustained minor injuries. The aircraft was registered to and operated by Fly High Aviation LLC under the provision of Tile 14 Code of Federal Regulations Part 91 as an air drop flight. Visual meteorological condition prevailed and a flight plan had not been filed. The flight originated from Boulder Municipal Airport (BJC)at 1645. The purpose of the flight was to drop 2 parachutists. The pilot stated that she fueled the airplane, performed a preflight and run up and departed. The climb to 13,000 feet was normal and subsequent drop was normal. She began a decent, dropped the manifold to 12 inches and applied carburetor heat. Passing through 9,000 feet, the airplane was about 3 miles from BJC when the pilot reduced power for a straight-in approach to runway 26. She then attempted to add power to adjust her decent rate, but there was no response. After performing a power loss checklist, she continued toward the runway thinking that she could glide to a safe landing. About 3/4 miles from the threshold she stated that a downdraft put her in a position that she would not make the runway. She choose an open filed and set up for a forced landing. Upon touchdown, the airplane rolled out nicely, but the pilot could not avoid colliding with some trees at the edge of the field. The left wing struck a tree, the airplane spun around After coming to a stop, the pilot quickly exited the airplane because she saw fuel pouring out of the left wing. Local witnesses stated that the weather was mild with little to no wind. The nearest weather reporting station was located at the Boulder County Airport (BJC), about 9 miles from the accident site. The weather METAR at 1649 local time reported scattered clouds at 7000 feet and broken clouds at 14,000 feet, wind from 110 degrees at 3 knots, and 50 miles visibility. METAR KBJC 092249Z 11003KT 50SM FEW070 BKN140 33/M07 A2992 The pilot held a commercial certificate with ratings for single-engine and multi-engine airplanes. She had about 556 total flight hours, of which, 59 hours were in the Cessna 182. She held a valid Class 3 medical certificate without waivers or limitations. She was employed by the operator to pilot sky diving flights. The airplane was transported to Greeley,Colorado for a more detailed examination of the engine. Upon general inspection, no abnormalities were observed. No evidence of debris, obstructions, or water contamination was identified in the airframe fuel gascolator. About 8.5 quarts of oil was in the engine. Some oil residue was found on the belly skin of the airplane, and was identified to have originated from an aftermarket oil drain installation. The throttle linkage to the induction box was adjusted and the engine was test run while still in the airframe mounts. It started normally and ran at various power settings with no anomalies noted. Throughout the engine run, the engine accelerated normally without hesitation. A magneto RPM drop check was normal. The accident site was located about 1.5 miles northeast of the Boulder County Airport. Tire impressions in the grass of an open field showed a landing roll in a north westerly direction until the airplane collided with trees. First responders noted that upon their arrival, fuel was found leaking. The leading edges of both wings had impact damage corresponding to impact with the trees. The nose gear assembly was folded up into the belly of the airplane. On site examination of the flight controls confirmed continuity from the cockpit to all flight control surfaces. The engine was attached to the airframe and exhibited some impact damage to the belly under the engine compartment. When moved by hand, the throttle linkage to the air induction box did not move smoothly and was stiff, however, the area just underneath the box appeared to be pushed upward from impact forces. On first sight, the linkage to the induction box did not appear to have been altered by impact forces, but since the damage underneath the engine compartment was so close to the box, it is undetermined whether or not the throttle linkage anomaly was present before impact. The propeller assembly remained attached to the engine hub and both blades were straight with little damage. About 5 gallons of fuel was drained from the left fuel tank and about .5 gallons were drained from the right fuel tank. The fuel selector was found in the 'Both' position. Because of the fuel leakage due to impact damage, there was no way to quantify exactly how much fuel was onboard at the time of the accident.

Aircraft

Registration
N8717T
Reported as
Cessna 182C
Category
Airplane
Serial number
52617
Built
1960
Airframe hours
3,853
Engine
Cont Motor O-470 SERIES, 230 horsepower, reciprocating
Damage
Substantial damage
Flight
Skydiving · Part 91
Operator
Fly High Aviation
Registered owner
Fly High Aviation
Airworthiness certificate
Standard, Normal
Last inspection
Annual · July 28, 2011
Departed
KBDU · Boulder, CO
Destination
KBDU · Boulder, CO

Matched to the registry by N-number and the event date; the registry’s history has gaps, so older matches can be wrong. Compare the reported make and model.

Flight crew

As NTSB recorded them. NTSB leaves out names.

Role
Pilot
Age
36
Injuries
Minor
Certificate
Commercial
Airplane ratings
Single-engine land, Multi-engine land
Instrument ratings
Airplane
Medical
Class 2, Without waivers/limitations
Last flight review
August 7, 2009
Seat
Left
Flight hours
556 total · 59 in this make and model · 453 as pilot in command · 57 in the last 90 days · 47 in the last 30 days · 7 in the last 24 hours

Weather

Conditions
Visual (VMC) · Day
Wind
250° at 10 knots, gusting 19
Visibility
10 statute miles
Temperature
91 °F, dew point 19 °F
Altimeter
29.92 inHg
Observed at
BJC, 9 nm away

Docket · 10

The files NTSB released with the investigation on September 2, 2014, on NTSB’s docket system: statements, records, photos and specialists’ reports. 14.3 MB in all.

FAA reports on this event · 1

The FAA’s own accident and incident reports, matched to the aircraft by N-number and date.