Athol, ID, USA
N3367F
Cessna 182J
While in cruise flight, the pilot heard a loud clank, and then saw the oil filler door on the nose cowl pop open. Immediately thereafter, the engine lost a significant amount of power, and the windshield began to be covered with a film of oil. The pilot therefore elected to make an emergency landing on a nearby road, and although the initial touchdown was successful, the oil coated windshield made it impossible for the pilot to seeing where he was going. Ultimately the aircraft departed the side of the road and impacted a culvert, whereupon the nose wheel strut collapsed. It was ultimately determined that the number five connecting rod cap bolt failed in overload after its retaining nut backed off to a point where it was retained by only two threads. Further examination of the nut and cotter pin revealed that the cotter pin retaining the rod bolt nut had experienced fatigue crack propagation failure in two location. It was determined that both cracks initiated at locations were the insufficiently torqued connecting rod cap bolt nut had vibrated against the cotter pin surface.
On July 5, 2003, approximately 1400 Pacific daylight time, a Cessna 182J, N3367F, experienced a gear collapse during a forced landing on a road about three miles northwest of Athol, Idaho. The private pilot and his two passengers were not injured, but the aircraft, which is owned and operated by the pilot, sustained substantial damage. The local 14 CFR Part 91 personal pleasure flight, which departed Coeur d' Alene Air Terminal, Coeur d' Alene, Idaho, about 15 minutes earlier, was being operated in visual meteorological conditions. No flight plan had been filed. The ELT, which was activated by the sequence of events, was turned off at the scene. According to the pilot, while he was in cruise flight, he heard a loud "clank", and saw the oil filler door on the engine cowling pop open. Soon thereafter the engine lost a significant amount of power, and oil spread across the front windscreen of the aircraft. The pilot therefore elected to attempt a forced landing on a nearby narrow paved road. As he descended toward the road, a thick coat of oil covered the windshield, and because he could see almost nothing through the oil film, he side-slipped the aircraft toward the point at which he wanted to touch down on the road. When he arrived at the location where he should begin his landing flare, the pilot straightened out the aircraft and made a successful touchdown. Although the touchdown was without incident, the pilot could not see the road through the oil film on the windshield, and therefore was unable to maintain a rollout track that would keep the aircraft on the road. During the landing roll, the aircraft departed the left side of the roadway, and the nose gear collapsed when it encountered a culvert. A post-accident NTSB-directed and FAA-monitored teardown inspection of the engine was conducted at Teledyne Continental Motors (see attached Engine Analysis Report). That inspection revealed that one of the number five connecting rod cap bolts had fractured at a point where the cotter pin hole passes through the bolt shank. During that inspection the cotter pin was found in three pieces in the oil sump. The subject bolt, cotter pin, and nut were further inspected and analyzed by Teledyne Continental Motors Metallurgical Laboratory (see Teledyne Continental Motors Metallurgical Report), and it was determined that the two fractures on the cotter pin where consistent with the propagation of fatigue cracks. It was further determined that there were wear scars on both the cotter pin and the castellated nut at a location where they had repetitively contacted each other. The fatigue cracks on the cotter pin emanated from the aforementioned contact areas. Further inspection of the wear marks on the bolt revealed that at some point in time the castellated nut had backed off of the bolt to a point where it was only attached by two threads, whereupon the bolt failed in overload. According to the Continental Motors Metallurgical Laboratory, the repetitive contact wear marks on the cotter pin were consistent with the nut being free to rotate as a result of insufficient torque being applied at the time of installation. Both Continental Motors reports were submitted to the NTSB Materials Laboratory for review, and it was concluded that the Engine Analysis Report adequately documented the condition of the disassembled engine parts, and the Metallurgical Report conclusions were supported by the facts.
The failure of one of the number five connecting rod cap bolts during cruise flight due to the associated number five rod cap bolt nut being insufficiently torqued at the last major overhaul. Factors include a culvert alongside the road where the pilot found it necessary to execute his emergency landing and the restriction of the pilot's forward vision due to a film of oil on the windshield.
Source: NTSB Aviation Accident Database
Aviation Accidents App
In-Depth Access to Aviation Accident Reports
