Accident Overview
On April 18, 2023, at 0913 eastern daylight time, a Rockwell International 112 airplane, registration N12RX, was substantially damaged in an accident at Miami Executive Airport (TMB), Miami, Florida. The commercial pilot was not injured. No flight plan was filed for the personal flight conducted under Title 14 Code of Federal Regulations Part 91.
Flight History
The pilot had been checked out in the airplane the previous week and this was her first flight in it. After completing three uneventful touch-and-go landings at North Perry Airport (HWO), Hollywood, Florida, she noticed the transponder was not functioning. She made a full-stop landing and contacted the owner, who arranged for repairs at an avionics shop at Miami Executive Airport. Before departing, she received air traffic control clearance to fly from HWO to TMB without a transponder. The flight was normal, and she was cleared for a straight-in approach to runway 9L.
Landing and Collapse
The pilot reported extending the landing gear and observing all three gear-down indicator lights illuminated. She felt the gear lock into place. Upon touchdown, she sensed the airplane was “unbalanced,” with the nose and left main gear on the ground but the right main gear feeling not fully extended. The airplane veered off the runway and came to rest on the grass. The right wing sustained substantial damage. The nose and left main gear remained extended, and hydraulic fluid was seen on the airplane’s belly streaming toward the tail. The pilot stated she conducted a thorough preflight inspection and saw no external hydraulic fluid before the flight.
Wreckage Examination
Postaccident examination at a maintenance facility revealed a small amount of hydraulic fluid in the reservoir. Manual operation of the landing gear handle produced no extension or retraction due to lack of hydraulic pressure. After adding fluid, the gear functioned normally through full cycles, and no mechanical anomalies were found. However, a hydraulic fluid leak was observed from the hydraulic power pack. Maintenance records indicated the power pack had been recently overhauled and installed about 1.8 flight hours before the accident.
The hydraulic power pack was shipped to the overhaul company and tested under FAA supervision. Bench testing showed it functioned normally during gear extension but could not hold pressure during retraction. The overhaul company noted that such pressure loss is not uncommon after a gear collapse, as back pressure can tear the check valve’s O-ring. Disassembly revealed a large tear consistent with fluid flow direction during the collapse, as well as a smaller tear in the middle of the O-ring. The company could not determine the direction of the smaller tear. The NTSB examined the O-ring under magnification but could not determine the tear direction.
Hydraulic System Analysis
The landing gear system is designed so that hydraulic pressure holds the gear up when selected. Inadequate fluid prevents retraction, causing a “bump” and an amp meter spike. The pilot reported normal retraction. When the gear is selected down, the system uses mechanical locks to hold it in place, not hydraulic pressure. A microswitch activates the gear-down indicator lights when the gear is fully extended. During postaccident testing, the indicator lights illuminated green when the gear was extended and turned off when retracted, so no further microswitch timing verification was conducted.