Accident Summary
On June 16, 2024, about 0741 mountain daylight time, a Tecnam P2006T airplane, registration N968GV, was substantially damaged when it was involved in an accident near Larkspur, Colorado. The flight instructor and pilot receiving instruction were seriously injured. The airplane was being operated as a Title 14 Code of Federal Regulations Part 91 instructional flight.
Flight Sequence
The flight instructor stated that he and the commercial-rated pilot receiving instruction were completing a multi-engine training flight, their first together. The instructor had 115 flight hours in the accident make and model, all as an instructor. The pilot receiving instruction had 2 flight hours in the same make and model, his only multi-engine experience.
During the first portion of the flight, they completed five full-stop, taxi-back landings at Centennial Airport (APA) in Englewood, Colorado. After the final landing, they proceeded southwest and climbed to 10,800 ft mean sea level (about 4,500 ft above ground level) to practice one-engine-inoperative (OEI) training procedures in the North Perry practice area. They initially completed directional control exercises and multiple simulated engine-out emergencies. Next, they shut down the left engine by turning the left ignition switches to OFF. With the engine secured and the propeller feathered, the pilot receiving instruction maneuvered the airplane until they attempted to restart the engine. They referenced the engine restart checklist and attempted to restart but were unsuccessful. After waiting about 5 seconds, they engaged the starter buttons again and the engine restarted successfully. They slowly increased the left engine throttle and completed the cruise checklist before proceeding back toward APA.
While en route, the flight instructor noted that the airplane required additional right rudder to maintain control. The pilot receiving instruction took over and confirmed. The instructor noted that the left engine coolant temperature and rpm had decreased, so he took back the controls and proceeded to Perry Park Airport (CO93) in Larkspur, about 4 nautical miles south. After completing a 180° turn to south, he secured the left engine and feathered the propeller. The airplane was difficult to control and rapidly losing altitude. When he realized they could not reach CO93, he set up to land on Interstate 25 (I-25). Just before landing in the southbound lanes, he pitched up and banked left to avoid hitting southbound vehicles. The airplane climbed over the traffic, then impacted a marshy area east of I-25.
The pilot receiving instruction reported that when they turned toward CO93 and secured the left engine, they were not sure if the propeller was fully feathered.
ADS-B data indicated they departed APA about 0617 and completed five full-stop landings. At 0715, after the fifth landing, they departed southwest and climbed to 10,800 ft msl. The airplane was in the North Perry practice area for about 10 minutes between 10,200 ft msl and 10,800 ft msl, before turning north toward APA. In the next 3 minutes, the airplane descended about 2,000 ft before making a 180° turn toward CO93. After completing the turn, the airplane was about 1,600 ft agl and 4 nm from CO93. In the next 2 minutes, the airplane continued south over I-25 before the forced landing. The final ADS-B point was recorded 1.1 nm from CO93 about 200 ft agl.
Witness videos showed the airplane descending over I-25 with the right propeller rotating and the left propeller not rotating. The left wing struck a road sign, veered left, and climbed over oncoming traffic. The end of the accident sequence was not captured in the video.
The airplane came to rest inverted in a swampy area 0.17 nm east of the runway at CO93 and sustained substantial damage. The fuselage was inverted and folded on top of the wings. The engines remained attached to the nacelles. The right propeller blades were fractured. The left propeller blades were relatively undamaged and appeared to be feathered.
Postaccident Examination
Examination revealed that the left propeller lever was found retarded but not in the feathered position. The lever sustained damage and was bent right about 90°, and the pedestal upper cover was bent to the right in the same area. The left throttle lever was found retarded about mid travel. The carburetor heat levers were positioned to OFF. Both engines were examined and prepared for functional test runs; both ran successfully at various power settings. No preimpact mechanical malfunctions or failures were found that would have precluded normal operation.
The airplane’s Garmin G1000 avionics were removed and sent to the NTSB Vehicle Recorder Laboratory for data extraction; the units did not record any engine parameter data.
Other Information
A review of the Carburetor Icing Probability Chart from FAA Special Airworthiness Information Bulletin CE-09-35 indicated that the atmospheric conditions were conducive to the formation of serious icing at glide power settings.
The aircraft flight manual, Section 4 – Normal procedures (2.2 Single engine training), stated that the best practice is to retard one engine to simulate a dead engine, with propeller lever full forward and throttle lever set at 13.5 in Hg MAP at 70-90 KIAS and 2,000-4,000 ft density altitude. It also stated that shutting down an engine for training shall not become a habit, and engine shutdown to perform OEI should be executed only when required by regulations.