NTSB Factual Report

On August 4, 2013, about 1210 eastern daylight time, a Mooney M20R, N1034S, was substantially damaged during a precautionary landing at Tallahassee Regional Airport (TLH), Tallahassee, Florida. The private pilot and passenger were not injured. Visual meteorological conditions prevailed, and the airplane was operating on an instrument flight rules (IFR) flight plan. The flight, which had originated from TLH about 1200, was destined for Bartow Municipal Airport (BOW), Bartow, Florida. The personal flight was conducted under the provisions of Title 14 Code of Federal Regulations Part 91.

After receiving his IFR clearance, the pilot departed from runway 36 at TLH. He contacted the departure air traffic controller shortly thereafter and was cleared to climb to 5,000 feet. As the airplane climbed through 2,500 feet it entered the clouds, and near 5,000 feet, the pilot reported hearing an "indescribable noise" in his headset. Immediately thereafter, the primary flight display and the multi-function display lost power. The pilot assumed that the total loss of electrical power was due to a short circuit, given the abrupt nature with which the power loss occurred.

The pilot subsequently descended the airplane below the clouds, and once in visual meteorological conditions, used a portable electronic device to navigate back to TLH. During the return flight, the pilot was concerned about a possible electrical fire and smoke in the cockpit, and wanted to land the airplane as soon as possible. As such, he did not perform the emergency procedure for a manual extension of the airplane's electrically actuated landing gear. Upon reaching the airport, the pilot observed the green light gun signal from the air traffic control tower and landed the airplane on runway 36 with the landing gear retracted. The fuselage structure was substantially damaged during the landing.

A Federal Aviation Administration inspector examined the airplane following the accident. The inspector powered up the airplane's electrical system normally utilizing the number 1 battery, and the primary flight display operated normally. The inspector noted that the number 2 battery was inoperative. The inspector also noted that the landing gear actuator circuit breaker was engaged (not tripped or pulled). The airplane's entire electrical system was subsequently examined in detail by a maintenance facility. No discrepancies were found with the system, with the exception of an internal electrical short of the number 2 battery.

According to the electrical system description provided in the airplane's pilot operating handbook:

Two 24-volt 10-ampere-hour storage batteries (in the tailcone) and one 100 ampere self-rectifying alternator (produces 99 amps) suppl[y] electrical power for equipment operation. The No. 1 battery, left side of the tailcone, is normally used as the primary to sustain the electrical system and to start the aircraft. The No. 2 battery, right side of the tailcone, is normally considered as a backup and is kept in a fully charged condition by trickle charge, through a diode system.

Should the No. 1 battery be depleted to the point of being unable to supply adequate power for system needs, it may be de-selected from the system and the No. 2 battery selected on line by pushing the rocker switch marked BAT-1/BAT-2, on the circuit breaker panel, from the BAT-1 to BAT-2 position. The MASTER switch still controls battery power to the buss from either position. With the BAT-1/BAT-2 switch in the No. 2 position the No. 1 battery will be recharged (trickle charged) through the diode system. Alternate between #1 and #2 batteries, as desired, to keep both active.

The emergency procedure for a suspected fire in-flight stated:

Master Switch OFF

Alternator Field Switch OFF

Cabin Ventilation OPEN

Heating Controls CLOSED

LAND AS SOON AS POSSIBLE

If electrical power is essential for flight, attempt to identify and isolate the faulty circuit as follows:

Master Switch ON

Alternator Field Switch ON

Select ESSENTIAL switches ON one at a time; permit a short time to elapse before activating an additional circuit.

The emergency procedure for a failure of the landing gear to extend electrically stated:

Airspeed 140 KIAS or less

Landing Gear Actuator Circuit Breaker PULL

Landing Gear Switch DOWN

Gear Manual Emergency Extension Mechanism LATCH FORWARD/LEVER BACK

T-Handle PULL (12 to 20 times) and RETURN until gear is down and locked

GEAR DOWN light ILLUMINATED;

STOP when resistance is felt

Visual Gear Down Indicator CHECK ALIGNMENT by viewing from directly above indicator

NTSB Probable Cause

The pilot's failure to troubleshoot the in-flight electrical problem and restore power using the operable redundant battery and his decision not to manually extend the airplane's landing gear, which resulted in a gear-up landing. Contributing to the accident was an internal electrical short of the No. 2 battery, which resulted in a total loss of electrical power.