Incident Overview
On March 20, 2016, at 1646 mountain daylight time, a Cessna 172RG airplane (registration N6402V) landed with its landing gear retracted at Greeley-Weld County Airport (GXY) in Greeley, Colorado. The pilot was not injured, and the airplane sustained minor damage. The aircraft was registered to and operated by Northern Skies Aviation Inc. under 14 CFR Part 91 as a personal flight. Day visual meteorological conditions were present at the time of the incident.
Flight Sequence
The flight departed at 1330 from Gillette-Campbell County Airport (GCC) in Gillette, Wyoming, without a flight plan. The intended destination was Colorado Plains Regional Airport (AKO) in Akron, Colorado. According to the pilot, he diverted to GXY after the left landing gear did not extend during arrival at AKO. Following unsuccessful attempts to extend the landing gear, the pilot elected to perform a gear-up landing at GXY.
Examination Findings
Examination by Federal Aviation Administration (FAA) inspectors revealed that the left main landing gear actuator assembly (part number 9882015-2) housing was cracked across the forward attach bolt hole. The crack allowed the actuator bore to open sufficiently such that the piston would not engage the landing gear pivot sector adequately for gear extension. This failure mode resulted in the inability to fully raise or extend the landing gear, whether using the normal method or the emergency hand pump.
Maintenance History
The airplane's main landing gear was subject to FAA Airworthiness Directive (AD) 2001-06-06, which required inspections for cracks in landing gear pivot assemblies. This AD was complied with for the airplane on May 25, 2001. The failed landing gear actuator assembly was originally installed with the airplane, which had a total time of 6490.1 hours.
Subsequent Actions
To address initial and repetitive inspections of the landing gear actuator assembly, the FAA had published maintenance alerts in prior years, and Textron published service bulletins in 2001 and 2007. Following this incident, the FAA released Special Information Airworthiness Bulletin (SAIB) CE-17-16 for Cessna 172RG, R182, TR182, FR182, and 210/T210/P210-series airplanes. The SAIB emphasized the importance of inspecting main landing gear actuator assemblies and recommended compliance with Textron Supplemental Inspection Document (SID) 32-10-01, which directs a combination of visual, fluorescent penetrant, and eddy current inspections, depending on the airplane model. The SAIB included initial and repetitive inspection intervals and recommended an inspection after an unplanned event, such as a hard landing.