Accident Details
On November 14, 2012, about 1915 eastern standard time, a Cessna 172RG, N9985B, was substantially damaged during an emergency landing at Blue Grass Airport (LEX), Lexington, Kentucky. The airplane was operated by Eastern Kentucky University under 14 CFR Part 91. The certificated flight instructor and a private pilot were aboard and were not injured. Night visual meteorological conditions prevailed, and an instrument flight rules flight plan had been filed. The flight departed Madison Airport (I39), Richmond, Kentucky, at 1730, with an intended destination of Warren County Airport/John Lane Field (I68), Lebanon, Ohio.
Landing Gear Failure
During the approach to I68, the left main and nose landing gear extended normally, but the right main landing gear did not extend. Attempts to raise the gear were unsuccessful; the left main and nose gear would not retract. Manual emergency gear extension also failed—no resistance was felt while pumping. The pilots decided to divert to LEX. On landing, the airplane veered off the runway and came to rest in the grass. The right stabilator was substantially damaged.
Examination Findings
A Federal Aviation Administration inspector examined the wreckage and found the hydraulic reservoir devoid of hydraulic oil. The landing gear system revealed a hydraulic hose with a full-thickness rupture and evidence of oil leakage. The NTSB Materials Laboratory examined the hose and found the rupture consistent with environmental stress crack growth. The crack likely initiated on the interior near the fitting collar. The hose material was a polyester/polyurethane co-polymer with polyester cloth sleeving. The hose construction did not match any of the manufacturer’s three specifications and was similar to hoses used in the automotive industry.
Maintenance History
According to airframe maintenance records, a 100-hour inspection performed on November 2, 2012, included three landing gear retraction tests and a check of the emergency extension system. The aircraft was deemed airworthy after the inspection. The Cessna 172RG Pilot’s Operating Handbook specifies procedures for landing gear failure, including use of the emergency hand pump. A Cessna Service Letter (SN85-54) dated November 27, 1985, revised the hydraulic hose replacement interval from 5 years to “on condition.” The Cessna Continued Airworthiness Program required inspection every 1000 hours or 3 years. The maintenance records provided could not determine if the hose had been inspected within the required timeframe.