NTSB Factual Report

HISTORY OF FLIGHT

On August 31, 2012, about 1448 Pacific daylight time, a Cessna 177RG, N300ZX, was substantially damaged during a runway veeroff in the landing rollout on runway 35 at Olympia Regional Airport (OLM), Olympia, Washington. The owner/pilot was not injured. The personal flight was conducted under the provisions of Title 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed, and no flight plan was filed for the flight.

According to the pilot, he based the airplane at OLM, and was returning there after a flight to a nearby airport. The pilot described the accident touchdown as "uneventful." About 150 feet beyond the touchdown point, the airplane abruptly swerved to the right, and the pilot unsuccessfully attempted to counter the swerve with left rudder and brake. The airplane departed the side of the runway, and all three landing gear collapsed or otherwise failed.

Subsequent examination of the airplane by a Federal Aviation Administration (FAA) inspector determined that the propeller, landing gear, airplane belly skins, and one elevator were damaged. The nose landing gear (NLG) components were retained for further examination.

PERSONNEL INFORMATION

FAA information indicated that the pilot held a private pilot certificate with an airplane single-engine land rating. The pilot indicated that he had a total flight experience of about 800 hours, including about 350 hours in the accident airplane make and model. His most recent FAA third-class medical certificate was issued in July 2012

AIRCRAFT INFORMATION

FAA information indicated that the high-wing, retractable landing gear airplane was manufactured in 1971, and was first registered to the pilot in October 2000. Airplane maintenance records indicated that landing gear maintenance, including replacement of some components and extensive re-rigging of the nose landing gear, was completed in June 2012. The most recent annual inspection was completed in July 2012.

The landing gear was operated by a lever in the cockpit, which commanded hydraulic pressure to be routed to extend or retract the three landing gear. The two main landing gear assemblies rotated and translated forward for gear extension, and retracted aft into wells in the aft fuselage. The main landing gear downlocks were electrically powered. The NLG assembly also rotated and translated forward for extension. The NLG design used a combination of an overcenter mechanism and system hydraulic pressure to lock the NLG in the extended position

METEOROLOGICAL INFORMATION

The OLM 1454 automated weather observation included calm winds, visibility 10 miles, clear skies, temperature 21 degrees C, dew point 8 degrees C, and an altimeter setting of 29.95 inches of mercury.

AIRPORT INFORMATION

According to FAA information, OLM runway 35 was paved with grooved asphalt, in good condition, and measured 5,500 by 150 feet. Airport elevation was 209 feet above mean sea level. The airport was equipped with an air traffic control tower, which was operating at the time of the event.

WRECKAGE AND IMPACT INFORMATION

The airplane came to rest upright, on its belly, on the unpaved region adjacent to the right side of the runway (relative to the landing direction). It was facing approximately the opposite direction of landing. The left wing, left horizontal stabilizer, aft fuselage, propeller, and all three landing gear were damaged.

The two main landing gear assemblies were found positioned essentially back into their near-retracted positions; only a small portion of each tire protruded beyond the outer mold line of the fuselage. The nose gear remained partially attached to the airplane, and was overextended forward to a near-horizontal orientation. In that orientation, the nose gear wheel and tire were located below and forward of the propeller arc.

The nose gear upper torque link was fractured at its attach point to the lower torque link. The right-side lug of the nose gear upper/aft drag link that mated with the tab of the lower/forward drag link was fracture-separated. The steering bungee (a portion of which consisted of a spring contained inside a tube/rod) was fractured at the end where it attached to the NLG strut.

The propeller did not display any damage signatures consistent with pavement contact. All three propeller blades displayed rubber transfer or impact damage consistent with striking the nose gear tire or wheel. The nose gear tire had two transverse (perpendicular to the wheel plane of rotation and tire tread) cuts in it, and the right side of the wheel had an impact gouge; all three were consistent with propeller blade strikes. The orientation and position of the nose gear assembly that would be required to align the propeller and tire/wheel contact points were not explicitly determined, but such contact would require overtravel of the nose gear assembly well beyond its normal "down and locked" position.

The left side rim of the nose gear wheel exhibited scuffing consistent with abrasion by a rough non-metallic surface such as asphalt, but the left side of the tire did not exhibit any such abrasion.

The presence or lack of skidmarks, or paint or metal transfer marks on the runway in the touchdown zone, or in the vicinity of the runway centerline, was not documented.

Some marks near the runway edge were partially documented. Two long rubber skid marks and one small paint transfer smear were observed on the runway near where the airplane came to rest. All three were arced, and approximately parallel to one another. Neither their origin points nor dimensions were documented. The two rubber skid marks appeared to originate towards the center of the runway, and curved east (right) to the east edge of the runway. The southernmost skid mark was heavy and well-defined, while the other skid mark was significantly thinner and more faint. The heavy skid mark continued as a gouge in the grass and dirt adjacent to the runway, and appeared to terminate near where the airplane's nose came to rest. A section of one edge of that skid mark, adjacent to where the airplane departed the side of the runway, also exhibited metal smearing consistent with wheel contact. The wheel/tire that produced the heavy skid mark was not determined by on-scene personnel. Although there was insufficient evidence to subsequently positively attribute that skid mark to a specific wheel position on the airplane, the available evidence was all consistent with the skid mark being produced by the NLG.

The narrow skid mark was situated approximately parallel to, and about 10 feet north of, the heavy skid mark. The narrow skid mark appeared to originate further from the center of the runway than did the heavy skid mark. The narrow skid mark terminated at the runway edge, and no continuation was apparent in the grass and dirt adjacent to the runway. The paint transfer smear appeared to measure about 1 foot by 3 feet, and was situated about 8 feet north of the narrow skid mark, and about 5 feet from the runway edge.

ADDITIONAL INFORMATION

Maintenance Information

According to the maintenance records, in December 2000, repairs to the skin, replacement of two antennae, and multiple checks of landing gear functionality, were completed. Those activities were consistent with maintenance actions required after a gear-up landing. No record of that event were located in the NTSB accident database, but none would be expected if the event was categorized as an "incident" by the NTSB. The maintenance records indicated that at that time, the airplane tachometer registered 2,105.49 hours.

Extensive maintenance on the landing gear system and components was completed on June 12, 2012. The records indicated that at that time, the airplane had a tachometer time of 2,457.2 hours. Work accomplished included replacement of hydraulic hoses, and repair or re-rigging of multiple landing gear system components, including the "right gear downlock hook assembly." On July 2, 2012 the most recent annual inspection of the airplane was completed by a different mechanic and facility than those which performed the landing gear maintenance. The records indicated that at that time, the airplane had a tachometer time of 2,469.22 hours, a "Hobbs" time of 2,020.2 hours, and a "TTAF" (total time airframe) of 2,469.22 hours.

At the time of the accident, the airplane tachometer registered 2,460.58 hours, and the hour meter registered 2,820.2 hours. The discrepancies between those observed values and those that appeared in the maintenance records could not be reconciled.

The pilot reported that the airplane had accumulated 1 hour between the time of the landing gear maintenance activity and the accident flight.

Wreckage Examination

About 10 days after the accident, the airplane was moved to and examined in a maintenance facility hangar at OLM by an FAA inspector and an aircraft mechanic of that maintenance facility. After transport, the airplane was raised on jacks to enable detailed examination, and possible functional checks, of the landing gear. After the airplane was raised, the right main landing gear (RMLG) leg free fell into the fully extended and locked position without any intervention by the personnel. The left main landing gear (LMLG) would not lock into its extended position, either first by freefall, or subsequently with hydraulic power applied to the airplane landing gear system. When a screwdriver was used to "pull" the LMLG "downlock mechanism," the LMLG locked into place into its fully extended position. The personnel did not investigate the LMLG downlock mechanisms further, because the RMLG downlock functioned normally, and a collapse of the LMLG was not reported by the pilot.

The NLG damage precluded any operational evaluation of the NLG system

The FAA inspector and the mechanic removed the fractured NLG components for shipment to the NTSB Materials Laboratory for failure analysis. The laboratory examination determined that all the failures were due to tensile overload, and no indications of pre-existing material deficiencies or mechanical failures were observed.

Previous Cessna 177 Landing Gear Problems

According to the 1991 edition of Aviation Consumer Used Aircraft Guide, the 1971 and 1972 model years of the Cessna 177RG were "plagued" by landing gear problems, primarily with the "main gear downlocks." It did not cite any problems with the airplane's steering system.

NTSB Probable Cause

A loss of directional control during landing for reasons that could not be determined because postaccident examination of the nose gear steering mechanism did not reveal any anomalies that would have precluded normal operation.