N4420KCurtiss Wright P-40E

On June 27, 2023, about 0759 mountain daylight time, a Curtiss Wright P-40E, N4420K, was substantially damaged when it was involved in an accident near Hamilton, Montana. The pilot was fatally injured, and the airplane sustained substantial damage. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight.

According to an airframe and powerplant mechanic, on the morning of the accident, the pilot conducted a preflight inspection of the airplane at Ravalli County Airport (HRF), Hamilton, Montana, and needed assistance to troubleshoot a starter problem. The mechanic stated that after he inspected the starter, the pilot started the airplane without further incident and continued his pretakeoff checks. He added that during his conversations, the pilot’s general mood was happy. Another mechanic reported that as the airplane taxied to the hold-short line for runway 35, the pilot performed a full run-up. After the pilot conducted magneto checks, the mechanic heard a 3-5 second engine surge. The pilot then continued and departed runway 35. Witnesses near the accident site reported that they observed the airplane depart to the north. During the initial climb, the airplane turned left to the west, and shortly after, it descended and impacted terrain in a nose-down attitude. Multiple witnesses reported that during the initial climb, there was a power loss event.

Examination of the accident site revealed that the airplane impacted terrain about ½ mile west of the departure end of runway 35 (see figure 1). The debris path was oriented on a heading of about 230° magnetic and was about 216 ft in length from the initial impact point to the main wreckage. All major components of the airplane were observed throughout the debris path. The fuselage came to rest upright on a heading of about 060° magnetic at an elevation of 3,615 ft mean sea level.

Figure 1. View of accident site in relation to the runway.

A postaccident examination of the airframe and engine revealed no mechanical anomalies that would have precluded normal operation. Flight control continuity was confirmed from the cockpit to each flight control surface. The reduction gearbox pinion gear was manually rotated and mechanical continuity was confirmed throughout the rotating group, valvetrain, and accessory section.

The pilot’s autopsy was performed by a medical doctor of the Montana State Medical Examiner, Missoula, Montana. According to the pilot’s autopsy report the pilot’s cause of death was blunt force and thermal injuries, and his manner of death was accidental.

The Federal Aviation Administration's Bioaeronautical Sciences Research Laboratory, Oklahoma City, Oklahoma, performed toxicological tests on specimens recovered from the pilot. The pilot’s postmortem toxicological testing detected Citalopram, N -Desmethylcitalopram, Albuterol, and Rosuvastatin.

Citalopram is a prescription medication commonly used to treat depression and anxiety. Major depression can cause cognitive impairment, particularly of executive function. By contrast, studies of citalopram have not established that it causes cognitive or psychomotor impairment. However, citalopram carries a warning that any psychoactive drug may impair judgment, thinking, or motor skills, and that users should be cautioned about operating hazardous machinery, including automobiles, until they are reasonably certain that citalopram does not affect their ability to engage in such activities. A pilot on citalopram may be considered for FAA medical certification via special issuance only, because detailed evaluation of the individual pilot’s condition is required, including assessment of the pilot’s cognitive function and response to medication. N-desmethylcitalopram is a metabolite of citalopram. Rosuvastatin is a prescription medication for cholesterol control that is commonly used to reduce cardiovascular risk. Albuterol is a prescription medication commonly used to relax tight lungs and improve wheezing and cough in conditions such as asthma and bronchitis. Rosuvastatin, aspirin, and albuterol are not generally considered impairing.

According to the FAA medical case review, the pilot's medical certification file contains multiple renewal letters, medication follow up checklists, and reports of formal evaluations of his condition through 2023, indicating successful management of his condition since 2014, on citalopram.

Upon touchdown, the World War II era tailwheel-equipped airplane experienced an uncontrollable swerve as the right main landing gear began to collapse. As the right main gear exited the edge of the runway, the airplane rocked forward onto its nose and the propeller and left wing tip impacted the ground. The airplane rocked back and came to rest partially off the runway in an upright and right wing low position. An examination of the landing gear retraction system revealed that the landing gear handle detent was contaminated with paint. Subsequently, the landing gear handle did not stay in the detent which resulted in the right landing gear downlock pin to partially retract, followed by the partial retraction of the right main landing gear.