NTSB Factual Report

HISTORY

On September 23, 2011, at 1615, eastern daylight time, a Cessna P210N, N210LE, registered to Silent H LTD and operated by an individual, incurred substantial damage when it impacted trees during a force landing in South Deerfield, Massachusetts. The pilot and passenger received serious injuries. Instrument meteorological conditions (IMC) prevailed and an instrument flight rules flight plan was filed for the 14 Code of Federal Regulations Part 91, personal flight. The flight originated from Barnes Municipal Airport (BAF), Westfield, Massachusetts, and was enroute to Hancock County-Bar Harbor Airport (BHB), Bar Harbor, Maine, about 1539.

According to the pilot, he completed a preflight inspection of the airplane with no anomalies noted. After takeoff he raised the landing gear and the gear warning horn remained on continuously. He reported to the controller at the tower that he may be returning to land. He had his passenger look for the gear warning horn circuit breaker, however about two minutes later, the warning horn stopped by itself. The pilot thought the gear horn issue was resolved and elected to continue to his destination of BHB. The air traffic controller gave the pilot further instructions to contact departure control and a frequency change was approved.

Immediately following the frequency change, the navigation systems failed, restarted, and failed again. The cabin fan, instrument lights, and cabin lights failed and the airplane suffered a total electrical system failure. At this point, the pilot believed that the airplane encountered turbulence, heavy rain, and he elected to climb above the weather. He reported the airplane seemed to receive strong gusts of wind upsetting the airplane; at one point, giving an indication of over 2,000 feet per minute descent. The pilot put the gear handle down and the flaps out in order to try to stabilize the airplane, but neither functioned. The pilot arrested the steep descent, elected to descend below cloud level, and make a precautionary landing. He saw a clearing in the clouds and made a “standard rate” spiral down through it. He broke out of the clouds about 2,700 feet mean sea level. He saw an open field and maneuvered for the downwind with the intent to land there. On the approach to the field, about 300 feet above ground level, the airplane porpoised three times; the pilot increased engine power, however, the airplane porpoised again. The nose of the airplane struck the top of a tree, the airplane impacted the ground, and came to rest about 200 feet past the tree.

PERSONNEL INFORMATION

The pilot held a private pilot certificate with ratings for airplane single-engine land and instrument airplane. He was issued a third-class medical certificate on June 24, 2010, with limitation of must wear corrective lenses. He reported 1,452 total hours, of which 985 were in make and model of the accident airplane; 87 of those total hours were in actual instrument conditions.

AIRCRAFT INFORMATION

The pressurized, six place, high wing, serial number P21000825, airplane was manufactured in 1983 and issued a standard airworthiness certificate in the normal category. The airplane incorporated an optional dual alternator electrical system. The airplane was equipped with a Continental Motors TSIO-520-AF3B, 310 horsepower engine with a McCauley controllable pitch propeller. According to airplane’s maintenance records, the most recent annual inspection was performed on August 11, 2011. At the time of the accident the airplane had accumulated 2,985 hours of total time and the engine accumulated 350 since major overhaul.

The airplane was equipped with the following electrical operated equipment: Garmin GMX200 Color Multi-Functional Display (MFD) equipped with Electronic Charts, XM Weather, Traffic Information System (TIS) and XM Radio, a Garmin 530WAAS (Wide Area Application Services) , a Garmin SL30 #2 NAV/COM slim line unit, a Garmin GTX330, S-Mode Transponder, a Garmin Audio Panel GMA340, a Goodrich Avionics System WX-500 Stormscope, 6-Place Stereo Intercom with XM Interface (Weather and Stereo Music), a Garmin GDL69A, XM Weather, a factory weather radar pod Bendix King KN62A DME, an EDM800, 6-cylinder Engineering Monitoring System Shadin Fuel Flow, a HID (High Intensity Discharge) wing tip, nose taxi, and landing lights, a PS Engineering, PAV-80 Audio/Video, DVD/CD/XM Stereos System, 6-place jacks.

METEOROLOGICAL INFORMATION

The closest official weather observation was at BAF, which was 20 miles north of the accident site. At 1609, the automated weather observing system (AWOS) indicated wind from 130 degrees at 4 knots; visibility, 6 statute miles; light rain and mist; clouds broken 900, broken 1400, overcast 2200; temperature 22 degrees Celsius (C); dew point 20 degrees C; altimeter 30.04 inches of mercury.

WRECKAGE and IMPACT INFORMATION

The responding Federal Aviation Administration (FAA) inspector stated that the right wing was damaged and folded aft onto the fuselage and the left wing was bent aft. Flight control continuity was confirmed to all flight controls. The flap setting was checked with the flap actuator and they were positioned with about 20 degrees of flaps extended. The propeller was separated from the engine and the propeller bolts were pulled out of the flange on the crankshaft. The engine remained intact and attached to the fuselage. In addition, the No. 6 cylinder rocker box cover exhibited a puncture hole in it. Further examination revealed that the No. 6 intake valve and valve stem penetrated the cover and the head of the valve was resting on top of the cylinder.

TEST AND RESEARCH

An electronic JPI Engine Data Monitor, 700/800 model, was removed from the airplane and submitted to the NTSB Recorders Laboratory in Washington, DC, for data retrieval. The data revealed that there were no anomalies with the engine. However, the data indicated that the battery voltage decreased rapidly from 21 volts to 10 volts just prior to the end of the data, which coincided with the loss of electrical power.

A postaccident engine run with FAA oversight was conducted at the engine manufacturer facility. The No. 6 cylinder was replaced and the engine was placed in a test cell and operated successfully in the low, intermediate, and high rpm ranges. The No. 6 intake valve guide, intake valve, valve springs, retainer, and valve keys were sent to Continental Motors Engineering Department for metallurgical evaluation. The testing revealed that the valve spring retainer failed in overload. For further information, reference the metallurgical evaluation report in the docket for this accident.

In addition, the engine’s maintenance records revealed the engine was most recently overhauled was on July 21, 2009. During the overhaul, ECI part number 648045 pistons were installed. A review of work order documents revealed that the FAA certificated repair station that performed the work installed six complete AEC631397/TISN71.4ACA cylinder assemblies, of which incorporated AEC 648045 high compression pistons (incorrect pistons). According to ECI service bulletin 99-8-1, page 6, AEC631397/TIST71.4BCA complete cylinder assemblies, utilizing part number 648044 pistons, were to be installed on the engine. The installed pistons produced a high compression ratio, which the engine was not adjusted for.

The number 1 and 2 alternators and number 1 and 2 alternator control units were retained and examined by Cessna Aircraft Company with FAA oversight. Both alternator control units functioned in the areas of regulation, low voltage annunciation, overvoltage trip, and field current overload. The No. 1 alternator was tested and malfunctioned approximately 5 minutes into the dynamic test. The No. 1 alternator was disassembled for further examination, which revealed that the rotor body and slip ring exhibited discoloration. The stator was found with one phase of the windings that had been burned from the copper wire so that coils were shorted together. The brushes were visually examined and found to be in worn but in functional condition. The No. 2 alternator was not dynamically tested due to damage incurred in the accident that prevented rotational operation. The No. 2 alternator was disassembled and had burnt windings in the two phases of the stator. No other anomalies were noted with the No. 2 alternator.

A postaccident examination of the wreckage with FAA oversight of the airplane’s electrical system revealed that the alternator restart battery pack did not contain enough voltage to reenergize the alternator field in the event that an alternator failed. A functional test of the system was required every 25 hours to ensure it worked correctly. The batteries were required to be replaced annually or sooner if the alternators cannot be restarted under a heavy load electrical load. A review of the airplane’s maintenance records revealed that most recent documentation for the alternator restart system batteries change was on December 15, 2000.

A postaccident interview with the pilot revealed that he attempted to regain electrical power by cycling the alternator switches on and off. In addition, he attempted to energize the alternator’s field utilizing the pilot operating handbook procedure for a single alternator system instead of the dual alternator system. The dual alternator system emergency procedure is a supplement for the pilot’s operating handbook (POH). The emergency procedure for the dual system states to depress the ALT RESTART switch. In the interview, the pilot stated that he did not know about the ALT RESTART switch.

For the dual alternator system, the BEFORE TAKEOFF checklist in the POH supplement stated for the pilot to perform a functional check of the system. The checklist that was located in the cockpit did not contain this functional check, nor did it contain the emergency procedures part of the supplement. The complete supplement can be found in the docket for this accident.

NTSB Probable Cause

The failure of the electrical system due to an alternator failure during flight in instrument meteorological conditions, and the pilot’s inadequate preflight inspection and failure to use the approved checklist for the dual alternator system. Contributing to the accident was the inadequate maintenance because the alternator restart battery pack was not replaced annually, as required by the airplane service manual.