NTSB Factual Report

HISTORY OF FLIGHT

On June 07, 2006, about 1900 Pacific daylight time, a Cessna 182B, N2404G, experienced a loss of engine power and collided with a tree during a forced landing in El Dorado, California. The student pilot, who was additionally the registered owner, was operating the airplane under the provisions of 14 CFR Part 91. The student pilot and certificated flight instructor (CFI) sustained serious injuries; the airplane sustained substantial damage. The local training flight departed from Placerville Airport, Placerville, California, about 1745. Visual meteorological conditions prevailed, and a flight plan had not been filed.

During a telephone interview with a National Transportation Safety Board investigator, the CFI stated that the student pilot had recently purchased the airplane. She had been instructing the student about 2 times per week since he had purchased the airplane, equating to around 10 flights. The accident flight was to consist of basic maneuvering, including climbs and descents, specifically configuring the airplane for level flight after arresting such maneuvers. The student pilot had flown Cessna 172 series airplanes prior to purchasing the accident airplane and was practicing using the constant speed propeller, as well as managing the additional horsepower the engine produces.

On the day of the accident flight, when the CFI arrived at the airport the student pilot was already 75 percent through his preflight inspection. After an uneventful departure, the student pilot practiced maneuvering in a local practice area for over 30 minutes. The CFI then had the student restrict his outside view with a hood in an effort to simulate instrument meteorological conditions. Upon the direction of the CFI, the student pilot began a climb to 6,000 feet mean sea level (msl). During the climb the CFI noticed that the engine's revolutions per minute (rpm) seemed low, as if the propeller control was not in the full forward position. With the airplane over the north finger of Folsom Lake, the student pilot leveled at 6,000 feet msl.

After the student pilot slightly retarded the throttle and propeller controls, the engine began to surge. The surge, described as momentary revs of rpm, continued for several seconds and the engine subsequently quit. The CFI assumed control of the airplane and maneuvered south, on course to runway 13 at Cameron Airpark, Cameron Park, California. She configured the airplane at a best glide speed of about 75 knots, and began performing the troubleshooting checklist. She noted that the airplane's fuel quantity gauges indicated that the right tank had 1/4 fuel remaining and the left tank showed 1/2 tank remaining.

The CFI realized that the airplane would likely not make it to Cameron Park and opted to land at a private dirt airstrip in the area. She completed a traffic pattern at the airstrip, and while on the final approach leg, realized the airplane was above a normal glide path. She called for the student pilot to retract the flaps (which were extended 20 degrees). While over the airstrip, about 10 to 15 feet above ground level (agl), the airplane drifted to the left of the airstrip with a crosswind. The CFI corrected the airplane to the right and the airplane continued to the right side of the airstrip and collided with a tree. She thought that as she corrected to the right, the crosswind became a tailwind.

The CFI added that after the accident the student pilot told her that he had confirmed the fuel quantity prior to departure by inserting his finger inside the wing tanks and touching the fuel inside; he did not have any equipment to accurately measure the quantity. She additionally noted that the accident airplane was equipped with numerous speed modifications enabling the airplane to "float" during the landing flare.

The wreckage was located in trees about 20 feet east of the Turner Airstrip at an elevation of about 1,375 msl. The global positioning satellite (GPS) coordinates for the crash site were 38 degrees 44.952 minutes north latitude and 121 degrees 00.504 minutes west longitude.

METEOROLOGICAL INFORMATION

A local El Dorado weather recoding facility reported the following conditions at 1858: wind from the south-southwest at 7 miles per hour; temperature 86 degrees Fahrenheit; dew point 43 degrees Fahrenheit; and an altimeter setting of 29.78 inches of Mercury. A review of a carburetor icing probability chart placed the reported temperature and dew point at the far outer edge of the "light icing at glide or cruise power" area of the chart, adjacent to the area not known to be favorable for carburetor icing.

TESTS AND RESEARCH

Following recovery, the airplane was examined under the supervision of a Safety Board investigator at the facilities of Plain Parts, Pleasant Grove, California. Present to the investigation were technical representatives from both Cessna Aircraft Company and Teledyne Continental Motors (TCM).

The airplane was separated into four major components for the purpose of recovery. The wreckage consisted of the left and right wing, fuselage (with the engine attached), and empennage. Recovery personnel detached both wings from the fuselage at their respective inboard root, leaving the fuel sending unit wires exposed. The empennage was separated near the aft baggage bulkhead.

Engine

The engine had sustained moderate impact damage at the forward lower section consistent with the absorption of impact energy. An initial visual examination of the engine revealed no evidence of preimpact catastrophic mechanical malfunction or fire.

Investigators established the engine's internal mechanical continuity during rotation of the crankshaft and upon attainment of thumb compression. All cylinder combustion chambers were examined through the spark plug holes utilizing a lighted borescope. The combustion chambers remained mechanically undamaged, and there was no evidence of foreign object ingestion or detonation. The valves were intact and undamaged. There was no evidence of valve to piston face contact observed. The gas path and combustion signatures observed at the spark plugs, combustion chambers, and exhaust system components displayed coloration that the TCM representative stated was consistent with normal operation. Ductile bending and crushing of the exhaust system components was observed.

The spark plugs were secure at each position with their respective spark plug leads attached. The top spark plugs were removed, examined, and photographed. The spark plug electrodes remained mechanically undamaged, and according to the Champion Spark Plugs Check-A-Plug chart AV-27, the spark plug electrodes displayed coloration consistent with normal operation.

The carburetor was removed and found to be intact; there was no fuel present in the bowl or accelerator pump chamber. The fuel gascolator was removed and the glass casing was intact. There was no liquid present in the gascolator body. Investigators found debris in the screen consistent to plant material. The entirety of the debris consisted of a 2-inch by 2-inch layer.

The left and right magnetos remained securely clamped at their respective mounting pads. The ignition harness was attached at the respective magneto(s) and each spark plug. The magnetos were removed for examination and investigators attempted to produce spark at the distributor post by rotating the main drive manually. The right magneto did not produce spark when rotated. The left magneto would produce a spark when rotated that would ground to the outer circumference of the magneto body.

Fuel System

Investigators examined the fuel system and confirmed continuity in the fuel lines. The fuel inspection panels were removed and investigators felt the inside liner of the fuel bladders. The left fuel bladder had predominant creases and the right tank had slight bumps in various areas. The bladders were removed and inspected by cutting open the cell along the outer wall.

The left bladder was labeled as being manufactured by Cessna in April 1958. The bladder exhibited several distinct wrinkles peaking about 1-inch high at the most creased area. The most severe of the creases were two parallel wrinkles that measured about 35 inches in length and were situated from the far outboard of the bladder stretching diagonally to the middle of the bladder. The other significant creases were situated near the fuel pick up and stretched along the cord line about 29 inches in length. The fuel sending unit roller rested on one of the smaller crease about 0.6 inches tall. The right bladder was a non-Cessna bladder and appeared to have been replaced.

Magnetos

A complete teardown inspection of the magnetos was performed at a Federal Aviation Administration (FAA) approved magneto repair station in Van Nuys, California. Prior to disassembly, the Bendix 20 series magnetos were placed on a test bench. According to maintenance personnel at the facility, both magnetos operated within the manufacture's specifications and consistently produced spark over an 11-millimeter gap.

Disassembly of the right magneto revealed that the impulse coupling spring was not wound completely. The magneto was timed at 10 degrees, which according to maintenance facility personnel, was considered accurate timing. The coupling was a newer snap-ring version and appeared to be intact. The oil slinger was absent, but no oil was located in the cavity. The left magneto was timed at 8 degrees, which the maintenance personnel stated was the minimum limits and was considered slightly early. The impulse coupling spring was not wound completely. The impulse coupling was the older riveted version and appeared intact. The distributor block and gear were both intact.

Maintenance personnel at the facility stated that there were no anomalies found in either magneto that would have precluded normal operation at cruise flight; they did state that the inaccurate tension of the impulse coupling springs (not wound completely) could have made starting the engine difficult.

ADDITIONAL INFORMATION

A review of the maintenance logbooks revealed that on January 05, 1988, airworthiness directive (AD) 84-10-01 was marked as complied with. A note was made that the mechanic smoothed out the wrinkles of the bladder fuel cells at this time. On July 16, 2003, an entry states, "installed owner supplied fuel tanks [bladders] leak check good."

Airworthiness Directive 84-10-01, Bladder Fuel Cells Revision 1, was issued on October 4, 1986, and pertained to the serial number of the accident airplane. In pertinent part it states:

"To prevent power loss or engine stoppage due to water contamination of fuel system, accomplish the following:

(c) Within the next 50 hours time-in-service after the effective date of this AD, on all applicable airplanes, except models 190 and 195, conduct an inspection for fuel tank wrinkles in accordance with the following:

(1) Drain the fuel tanks.

(2) Note any wrinkles which retain fluid after draining. Remove diagonal wrinkles across the inboard rear corner in the vicinity of the fuel tank drain by installation of Cessna drain kit described in Service Letter SE84-9 dated March 23, 1984, or by replacement of the fuel bladder. Verify that no wrinkles exist in the tank sump drain area before returning the airplane to service.

(3) If wrinkles are found in the tank bottom at a location other than diagonally across the inboard rear corner, determine the amount of fluid which is trapped by these wrinkles in accordance with the following:

(i) Place the airplane in the normal ground (water) attitude.

(ii) Service tank(s) with enough fuel to completely cover bottom of tank surface. Drain Tank and note any wrinkles which retain fuel."

NTSB Probable Cause

A loss of engine power for undetermined reasons and encounter with trees during the forced landing.