History of Flight
On May 22, 2022, at about 1149 mountain daylight time, a Piper PA-32-260, N85CT, was substantially damaged when it impacted terrain near Broomfield, Colorado. The pilot and pilot-rated passenger were fatally injured. The flight was conducted under Title 14 Code of Federal Regulations Part 91 as a personal flight.
According to automatic dependent surveillance-broadcast (ADS-B) data, the airplane departed Erie Municipal Airport (EIK) on Runway 16. About 3,000 ft from the departure end, the airplane made a left turn, descended, and impacted terrain.
Two experienced pilots living along the flight path reported abnormal engine noises. One pilot, located about 800 ft from the departure end of Runway 16, observed the airplane pass at 50-100 ft above ground level. About 5 seconds later, he heard several popping noises. The second pilot, about 1,000 ft west of the accident site, reported hearing a "loud carburetor cough" followed by a "quieter carburetor cough" within 10 seconds before impact.
Aircraft Information
A review of maintenance logs showed an avionics upgrade completed on February 4, 2022, including installation of a Garmin G5 and Dynon primary flight/multi-function displays. The pilot-rated passenger assisted with the installation. The airplane flew about 22 hours between the upgrade and the accident. The purpose of the accident flight included troubleshooting an avionics issue.
Meteorological Information
Meteorological conditions were conducive to serious carburetor icing at glide power.
Wreckage and Impact Information
The airplane impacted a grassy area in a residential community. About 35 ft beyond the initial impact point, six propeller strike marks spaced about 1 ft apart were found on a paved road. The airplane bounced and struck a large tree about 100 ft from the propeller marks, causing the engine and cockpit area to separate from the fuselage.
All components were accounted for. Fuel recovered from the left main, right main, and right wingtip tanks showed no contamination. The fuel bowl contained clean fuel. The electric fuel pump and fuel selector functioned normally. Carburetor floats were unremarkable, and the inlet screen was debris-free.
The electric fuel pump switch was in the on position, and the primer pump handle was in and latched. Throttle and propeller controls were fully forward. The mixture control knob was extended about 1 inch from the panel. Carburetor heat position could not be determined.
Flight control cable continuity was established. The flap handle was at 10°. Pitch trim screw extension corresponded to partial nose-down trim.
The crankshaft rotated manually, producing normal valve movement. Thumb compression was achieved on 5 of 6 cylinders; the No.2 cylinder did not produce compression. Removal of the No.2 cylinder revealed carbon deposits between the exhaust valve and seat.
Postaccident examinations found no evidence of a mechanical failure or malfunction that would have precluded normal operation.
Additional Information
Performance Study
Data from the Dynon displays were compared between the accident flight and a previous flight from the same runway at a similar time of day. On the accident takeoff roll, engine power was slow to increase, and acceleration was limited. The accident takeoff rate of climb was 200-300 ft/min less than the previous flight. The airplane pitched up over 20°, about twice the pitch attitude of the previous takeoff, reaching a maximum altitude of about 230 ft agl before pitching down and impacting.
Exhaust gas temperatures (EGTs) for cylinders Nos. 1, 5, and 6 were 70°F, 65°F, and 130°F hotter, respectively, during the accident takeoff compared to the previous one. Cylinders Nos. 2, 3, and 4 had similar EGTs. Fuel flow was about 5 gph less on the accident takeoff (11 gph vs. 16 gph, about 45% lower). Engine RPM and manifold pressure were similar between the two takeoffs.
The reason for the lower fuel flow was not conclusive. One possibility was that the pilot(s) leaned the mixture during extended ground operations (over 1 hour) and forgot to enrich it before takeoff. Leaning would be appropriate to avoid spark plug fouling. Another possibility was carburetor ice, which can reduce fuel flow by disturbing the venturi effect. FAA Special Airworthiness Information Bulletin CE-09-35 indicates that carburetor icing probability was serious at glide power under the weather conditions.
Rejected Takeoff Information
The airplane owner's handbook indicates a takeoff distance (to 50 ft) of about 1,300 ft for the accident conditions. Inflight data showed the accident ground roll was about 2,300 ft. The FAA Airplane Flying Handbook notes that a rejected takeoff may be necessary if the airplane is not airborne by a predetermined point.
Medical and Pathological Information
Autopsies of the pilot and pilot-rated passenger were performed; the cause of death for both was multiple blunt force injuries. Toxicology testing for the pilot found no tested-for substances. For the passenger, urine tested positive for tamsulosin, morphine, hydromorphone, and dihydrocodeine, but these were not identified in cavity blood.