NTSB Factual Report

HISTORY OF FLIGHT

On June 29, 2014, about 0810 mountain daylight time, a Cessna 182Q, N132K, was substantially damaged when it impacted trees and terrain while maneuvering in the traffic pattern to land on runway 19 at Big Creek airport (U60), Big Creek, Idaho. The owner/pilot was seriously injured. The personal flight was conducted under the provisions of Title 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed, and no Federal Aviation Administration (FAA) flight plan was filed for the flight.

The pilot planned to fly his airplane, in a pre-arranged group of several other airplanes, into U60 to attend a fly-in breakfast event there. The airport was considered a "backcountry" airport, denoting that it is situated in mountainous terrain, and typically requires approach and/or departure procedures that are more demanding and less forgiving than most airports.

According to an eyewitness, who was part of the group, and who had already landed, he saw the airplane during the last 20 to 30 degrees of its turn from base to final, after it "came around the Hogback," a ridge parallel to and on the left downwind leg side for runway 19. The witness's impression was that the airplane was "really low and slow" for its position relative to the runway. He estimated that the airplane was at about "one third [of] the height" that an airplane would normally be for the base-to-final turn. However, the witness was not certain about how far out on the final leg the airplane was when it made the turn, and he allowed that it could have been significantly closer to the runway than was normal for that airport. The witness did not see the airplane long enough or well enough to observe its flap configuration. The witness stated that he observed the airplane pitch "immediately nose down and left" as it made the turn. He heard the application of "full [engine] power," and the airplane descended behind the trees.

According to the pilot, he had entered the traffic pattern, and was transitioning from the base leg to final when the airplane departed controlled flight, descended rapidly into the trees, and impacted the ground. The airplane came to rest inverted in a ravine forested by tall trees, about 800 ft short of the runway.

PERSONNEL INFORMATION

FAA records indicated that the pilot held a commercial pilot certificate with airplane single engine land and instrument airplane ratings. According to information provided by the pilot, he had approximately 1,267 total hours of flight experience, including approximately 520 hours in the accident airplane make and model. His most recent flight review was completed in December 2012, and his most recent FAA third-class medical certificate was issued in June 2012. The pilot reported that he had flown into U60 one time previously, about 2 years before the accident flight.

According to FAA records, in September 2009, the pilot was attempting to conduct a touch-and-go in the same airplane on a "182 yard" (546 ft) long gravel bar in the Willamette River near Newberg Oregon, which resulted in the airplane becoming "completely submerged" in the river.

AIRCRAFT INFORMATION

The airplane was manufactured in 1979 as Cessna serial number 18266782, with an original registry of N96609. It was purchased by the pilot in July 2007, and re-registered by him as N132K in February 2008.

FAA records indicated that between January and April 2008, the airplane was modified to incorporate numerous major alterations, primarily by means of FAA Supplemental Type Certificates (STCs). An STC is the FAA's approval of a major change in the type design of a previously type certificated product. STCs are primarily issued by FAA Aircraft Certification Offices (ACO).The STC changes incorporated into the accident airplane included, but were not limited to, installation of the following:

- Continental IO-550 engine

- 3-blade propeller

- Canards

- Wingtip extensions (37 inch span increase)

- Oversized wheels and tires

METEOROLOGICAL INFORMATION

The 0751 automated weather observation at McCall Municipal Airport (MYL), McCall, Idaho, located about 36 miles southwest of the accident site, included calm winds, visibility 10 miles, clear skies, temperature 8 degrees C, dew point 6 degrees C, and an altimeter setting of 30.08 inches of mercury.

AIDS TO NAVIGATION

The pilot used his portable GPS device, published guide information, and information from fellow backcountry pilots to navigate to the airport, and in its traffic pattern. The pilot's airplane was the last of a small, pre-coordinated group of airplanes that traveled from MYL to U60. All the other airplanes in the group had already landed when the accident occurred.

AIRPORT INFORMATION

According to FAA information, U60 was at an elevation of 5,743 ft above mean sea level (msl), and was equipped with a turf runway that measured 3,550 by 110 ft. The runway was designated 1/19.

The Idaho Division of Aeronautics (IDA) published a series of "Airport SOPs" (standard operating procedures) for many backcountry airports, including U60. The IDA U60 SOP suggested a left-hand traffic pattern with an altitude of 800 to 1,000 ft above the field elevation (AFE), which result in traffic pattern altitudes between 6,543 to 6,743 ft msl. The SOP also depicted a suggested arrival and traffic pattern ground track, which included an upwind leg offset to the west-northwest of the runway, a downwind leg offset about 1/2 mile from the runway, and a base turn location which resulted in a final leg length of approximately 1 mile. The IDA Pilot and Safety/Education Coordinator stated that the upwind leg was intended to enable the arriving pilots to view the airport and assess its conditions, traffic, and wind. He also noted that because the runway was not normally visible from the downwind leg, due to its obscuration by the Hogback Ridge, which was parallel to and east-southeast of the runway, the 1 mile final was intended to enable pilots to detect airborne or ground traffic sufficiently early to allow them to safely compensate for the traffic.

The IDA-prescribed traffic pattern, when flown at a traffic pattern altitude of 1,000 ft AFE, and utilizing a constant descent profile beginning at the point abeam the threshold, would result in a descent slope of about 400 ft per nm, or a descent angle of about 3.7 degrees. Based on that constant slope profile, the turn to base leg would occur at an altitude of about 6,343 ft msl (600 ft AFE), and the turn to final would occur at an altitude of about 6,143 ft msl (400 ft AFE). High terrain in close proximity to the airport could necessitate a slight offset of the final approach track to the east, in order to concurrently maintain the constant descent profile and adequate terrain clearance.

WRECKAGE AND IMPACT INFORMATION

FAA personnel arrived at the accident site on July 1, 2014; they were the only investigative personnel to examine the airplane on scene. According to FAA inspectors, the airplane came to rest in an inverted position in a heavily wooded area. They estimated the trees to be about 50 ft tall, and observed multiple tree fragments on top of the wreckage.

The wreckage was tightly contained, and all major components were accounted for on scene. The airplane was adjacent to a ground scar that was consistent with an engine and propeller impact. The right wing was fracture-separated from airplane at the root, and located just aft and outboard of the left wing, which remained attached to airplane. The aileron crossover/balance cable was the only remaining attachment between the right wing and the airplane. The nose landing gear assembly was found approximately 40 ft forward of the main wreckage area, and both main wheel and tire assemblies were fracture-separated from their respective landing gear struts. The engine cowl flaps were found in the closed position. All engine controls were found in the full forward position. The flap control handle was found in the full up position, but the flap position indicator needle was found near the 40 degree (full down) position.

The wreckage was recovered to a secure facility by recovery personnel, for detailed examination by Cessna, Continental Motors, FAA, and NTSB personnel. The right side of the airplane sustained the most damage. Aircraft recovery personnel detached the left wing from the fuselage, and the left flap from the left wing. The left aileron remained attached to the left wing. The right flap and aileron remained attached to the right wing.

Witness marks on the fuselage from the left flap indicated that the left flap was extended about 15 degrees at the time of impact. The right flap was wedged in a fixed position due to impact damage, and was found to be extended approximately 15 degrees. The flap jack screw measured 3 1/4 inches, which equated to 15 degrees flap extension.

The empennage was separated from the fuselage by recovery personnel. The vertical stabilizer and both horizontal stabilizers remained attached to the empennage, and all three stabilizers retained their respective control surfaces. Flight control continuity was established for the flaps, ailerons, elevators, and rudder. The two canards remained attached to the airframe. Each canard consisted of a fixed forward panel and a movable aft panel. Control continuity for the canards was established.

The engine mounts were fracture-separated, and the engine remained attached to the airframe only via control cables and wires. There was no external evidence of operational distress or other non-impact damage on the crankcase and cylinders. A borescope inspection of the cylinders did not reveal any anomalies with the cylinder barrels, pistons, valves, or valve seats. The crankshaft was manually rotated, and crankshaft and camshaft continuity was confirmed. Thumb compressions were obtained on all six cylinders, and sparks were obtained on all six top ignition leads, in firing order, during crankshaft rotation. Cockpit to engine control continuity was established. Most engine components and accessories were examined in detail, and no pre-impact anomalies were noted.

The propeller was fracture-separated from the crankshaft propeller flange. The three all-metal propeller blades remained attached to the propeller hub. All blades exhibited S-bending and blade twisting.

No pre-impact anomalies with the fuel system were observed. The cockpit fuel selector was found set to the left tank.

No pre-impact mechanical anomalies, failures, or deficiencies that would have precluded normal operation and continued flight were observed. Refer to the NTSB public docket for this accident for additional details.

ADDITIONAL INFORMATION

STC Modifications and Airplane Performance

The airplane configuration was significantly modified relative to its original FAA-certificated configuration. Aerodynamic changes consisted of a 37-inch increase in wing span, and new fixed and movable aerodynamic surfaces (canards) forward of the cockpit. Other major changes included a more powerful, heavier engine, a 3-blade propeller, and a 150 pound increase in maximum allowable takeoff weight, with resultant changes to the CG envelope. Each of these changes was accomplished via the FAA STC process.

Four of the five significant performance-related STCs were accompanied by FAA approved "POH Supplements," which contained information regarding the operation of the airplane as a result of the incorporation of the particular STC modification. According to the current holder of the canard STC (SA485SW), due to its "early" (1960s) origination date, no POH supplement was created for that STC, and there were "no performance changes" associated with that STC. In addition, although there was a separate POH supplement for the engine STC (SA00152WI) and the 3-blade propeller STC (SA00727WI), the SA00152WI POH supplement indicated that the 3-blade propeller installation was part of the engine installation and the related published performance.

The SA00152WI POH supplement indicated that the maximum flap extension was limited to 35 degrees; the original Cessna maximum flap extension limit was 40 degrees. The cockpit flap position indicator cited the maximum flap extension position as "FULL," and the investigation did not determine the actual maximum flap extension limit.

The only significant published POH change associated with the wingtip extension STC (SA00276NY) was a decrease in the Vne (never exceed speed) from the original Cessna value of 179 KIAS (knots indicated air speed) to 157 KIAS. The airplane's airspeed indicator yellow arc (caution range) and redline (Vne indication) had not been modified to reflect the lower Vne, but in accordance with the POH supplement, the instrument panel contained an annotation that presented the revised Vne.

The POH supplements from the engine installation STC (SA00152WI) and the gross weight increase STC (SA03608AT) each contained multiple performance-related changes, and many of those changes were to the same parameters, including climb speeds, maneuvering speeds, and stall speeds. Neither of the POH supplements accounted for the incorporation of the other STC, and neither informed the pilot as to which parameter set has precedence over the other one in the event of a conflict between the two. Review of the performance-related data from those two POH supplements revealed multiple differences between the two datasets.

The original Cessna climb speeds (Vx and Vy) were 57 and 78 KIAS respectively, the SA00152WI Vx and Vy were 59 and 83 KIAS respectively, and the SA03608AT Vx and Vy were 59 and 81 KIAS respectively. The airplane instrument panel contained an annotation that Vx was 57 KIAS, and Vy was 78 KIAS.

The original Cessna maneuvering speed (Va) was 109 KIAS at gross weight, the SA00152WI Va was 112 KIAS, and the SA03608AT Va was 111 KIAS. The airplane instrument panel contained an annotation that Va was 111 KIAS.

The SA00276NY POH supplement stated that the stall speeds with the wingtip extensions installed "are approximately the same as the basic aircraft." The original Cessna POH, and each of the POH supplements for SA00152WI and SA03608TA contained tables of stall speeds as a function of CG location, bank angle, and flap setting. The published SA03608TA stall speed values are only applicable to weights above the original Cessna maximum gross weight of 2,950 pounds. Comparison of the table values revealed that all three sources provided different stall speed values. The lower end of airspeed indicator white arc was in accordance with the original Cessna stall speed value, which differed from the two corresponding published STC values.

The four cited STC POH supplements contained limited information regarding takeoff performance. Neither SA00276NY (wing extensions) nor SA00152WI (engine/propeller) presented any takeoff performance information or remarks. SA00727WI (propeller) stated that takeoff performance would be "improved," but did not provide any data. SA03608 (gross weight increase) presented a takeoff distance table in the same format as the original Cessna table; the STC table indicated that takeoff distances would increase by about 12 percent.

The four cited STC POH supplements contained very limited data regarding landing performance. Neither SA00276NY nor SA03608AT presented any landing performance information or remarks. SA00727WI (propeller) stated that landing distances were "unchanged," but SA00152WI (engine/propeller) stated that landing distances were to be increased by 5 percent.

SA00152WI stated that 1 knot should be added to approach speeds. That increment was the only mention of approach speeds in any of the POH supplements, despite the fact that approach and traffic pattern speeds are primarily a function of stall speeds, and the existence of the above-described stall speed changes.

Additional detailed information can be found in the NTSB public docket for this accident.

STC Vendor Information

The engine, propeller, and canard installations were the major elements of a performance enhancement package marketed as the "King Katmai" C-182 conversion by the company Peterson's Performance Plus. The company's web site stated that it was the man

NTSB Probable Cause

The pilot’s execution of a traffic pattern that did not put the airplane in position for a normal final approach and the pilot’s decision to continue the landing attempt instead of initiating a go-around, which resulted in the airplane exceeding its critical angle-of-attack and experiencing an aerodynamic stall at an altitude too low to prevent ground impact.