History of Flight
On May 18, 2012, at approximately 1620 eastern daylight time, a Cessna 195A, registration N9859A, was substantially damaged during landing rollout following a precautionary landing after a loss of oil pressure. The flight departed Old Bridge Airport (3N6), Old Bridge, New Jersey, destined for Zelienople Municipal Airport (PJC), Zelienople, Pennsylvania. The certificated commercial pilot was uninjured. Visual meteorological conditions prevailed, and no flight plan was filed for the personal flight conducted under 14 Code of Federal Regulations Part 91.
According to the pilot, during cruise flight at 6,500 feet above mean sea level, the engine rpm began fluctuating by approximately 100 rpm, followed about 20 seconds later by a drop from 2,000 rpm to 1,700 rpm. The pilot observed the oil pressure gauge reading zero and declared an emergency with air traffic control, who informed him the nearest airport was 15 miles south. The pilot reduced engine to idle and set the propeller to low rpm to prevent engine seizure. The terrain consisted of mountain ridges with hills and narrow valleys, and the pilot doubted he could reach the nearest airport. He located an industrial park in a valley that had been Peterson Memorial Airport, closed since 1974, with half of the old runway remaining as a road oriented 090/270 degrees. He elected to land into an easterly wind, executing a steep approach with flaps and a forward slip. After touchdown, he applied maximum braking. During rollout, the left wing struck a standpipe, and the airplane nosed over, coming to rest at an approximate 60-degree nose-down angle, 75 feet beyond the east end of the road.
Aircraft Information
The accident aircraft was a high-wing, four-place, single-engine, fixed-gear, tailwheel-equipped airplane of conventional metal construction, powered by a 275-horsepower Jacobs R-755-B2 7-cylinder radial engine. It was manufactured in 1950. The most recent annual inspection was completed on April 18, 2012. At that time, the airframe had accrued approximately 4,524 total hours, and the engine had accrued approximately 370 total hours since major overhaul.
Meteorological Information
The 2053 recorded weather observation at Altoona-Blair County Airport (AOO), located 8 nautical miles southwest of the accident site, included wind variable at 6 knots, visibility 10 miles, clear sky, temperature 23°C, dew point 5°C, and an altimeter setting of 30.15 inches of mercury.
Wreckage and Impact Information
Post-accident examination by a Federal Aviation Administration inspector revealed substantial damage to the left wing, left main landing gear, and left horizontal stabilizer. A 1/2-inch metal oil line was found fractured.
Tests and Research
Examination of the fractured metal tube identified it as the rocker scavenge oil tube, part number 4426A, located between cylinders No. 4 and No. 5. It had failed in fatigue in the manufactured bend adjacent to the coupling sleeve and nut. The tubing was type "N" copper, which became available in 1943 and was no longer commercially available by 1979, indicating the tubing was at least 34 years old and likely reused. The tube assembly displayed bends and compression not specified on manufacturer drawings, consistent with being significantly bent to fit. The manufactured bends showed oval cross-section, not specified in drawings. Cracks propagated from the fracture face at the centerline of the tube, which was the larger dimension of the oval cross-section. Grooves on the straight section indicated rubbing on an adjacent component. Hardness testing showed the tubing at the fractured bend was slightly harder than a sample not subjected to bending, exceeding specified maximum hardness. The increased hardness may have been produced by original manufacturing or subsequent manipulation (work hardening).
Review of information from the International Cessna 195 club revealed 11 instances of copper tubing failures. Research indicated that common practice to alleviate work hardening involved annealing copper tubing by heating and cooling, but FAA Advisory Circular AC 43.13-1B did not include guidance on annealing copper tubing. The FAA Aviation Maintenance Technician Handbook discussed annealing but did not specify a procedure for copper tubing.
Additional Information
Following the investigation, the type certificate holder for the Jacobs Engine recommended inspection of copper oil drain lines within 25 hours for signs of leakage, cracks, or damage, and replacement with FAA-approved parts. They also recommended annual or 100-hour inspections until factory new parts were installed, and replacement of any drain line when time in service could not be verified, with a life not exceeding 1,400 hours. These recommendations were forwarded to the FAA Aircraft Certification Office for inclusion in a Service Bulletin.