Overview
On November 15, 2017, about 2007 eastern standard time, a Cessna 172RG retractable gear airplane, registration N6102R, sustained substantial damage during landing at Miami-Opa Locka Executive Airport (KOPF), Miami, Florida. The airplane was registered to South Florida Aviation Group, LLC and operated by the pilot under 14 CFR Part 91. The certificated commercial pilot and a safety pilot were not injured. Dark night visual meteorological conditions prevailed, and no flight plan was filed.
Sequence of Events
The pilot reported that the purpose of the flight was to practice instrument approaches for an upcoming Certified Flight Instructor Instrument check ride. While intercepting the glideslope for the ILS 9L approach into KOPF, she moved the landing gear selector to the down position, verified the gear position indicator light illuminated green, set flaps to 20 degrees, and completed the before landing checklist. About 500 feet above ground level (AGL), the GPS blinked, and all electrical power and radio communications were lost. The safety pilot set the transponder to squawk 7600. About 150 feet AGL, the instrument panel lights blinked and remained illuminated. The pilot then selected flaps to 30 degrees and configured the airplane for landing while the safety pilot attempted to contact the tower. The pilot moved the landing light switch to the on position, and immediately all electrical power was lost. After receiving a green light gun signal from the tower, the pilot continued the approach and visually verified that the main landing gear was extended. Upon touchdown, the right main landing gear collapsed, and the airplane departed the runway, sustaining substantial damage to the right horizontal stabilizer. The pilot stated that no electrical or landing gear warning lights were illuminated for the duration of the flight.
The safety pilot reported a similar sequence: about 1 to 2 miles before the final approach fix, they selected gear down and completed the checklist. The GPS began blinking on and off, but radio power remained. She set the transponder to squawk 7600 and attempted to contact the tower on the number two radio without success. The GPS briefly returned, then the pilot turned on the landing light and all electrical power was lost. She felt the airplane touch on the gear, then it began to sink and drift right. She stated that the landing gear was down, verified by the gear position indicator light.
Postaccident Examination
According to the pilot operating handbook, the landing gear extension, retraction, and main gear down lock release are accomplished by hydraulic actuators powered by an electrically-driven hydraulic power pack. Normal operating pressure is 1000 to 1500 PSI. The nose and main gear have positive mechanical down locks, with two position indicator lights. The system also includes a nose gear safety switch, an emergency extension hand pump, and a gear-up warning system.
A postaccident examination revealed that the airplane's battery had been depleted. No anomalies were found with the landing gear system or its actuators. However, when the landing gear position indicator light was pressed or the gear was in transit, the landing gear unsafe horn did not produce an audible warning. The engine was operated under NTSB supervision and started normally without hesitation. At idle, the ammeter indicated a slight discharge, but the low voltage warning light did not illuminate. At about 1700 RPM, the ammeter indicated a charge. With an electrical load applied (landing light, strobes, rotating beacon), the ammeter continued to indicate a charge. Examination of the low voltage warning light revealed one of the wire's conductors that transits the instrument panel was completely severed, with no evidence of burning or arcing.
Weather
The closest weather reporting facility was Miami-Opa Locka Executive Airport. At 1953, the METAR reported wind from 020° at 5 knots, visibility 10 statute miles, clear skies, temperature 75°F, dew point 70°F, and altimeter 29.93 inches of mercury.