Ballad of a Montana Mixmaster

The NTSB has released its preliminary report on a 03 May 2023 accident in which a Cessna P337H Pressurized Skymaster, registration N62PC, was substantially damaged during a forced landing near Laurel, Montana.

The accident flight was conducted under Part 91 in day VFR/VMC conditions.

According to the pilot, the accident fight—which had been planned as a cross-country excursion from Bozeman, Montana’s Bozeman Yellowstone International Airport (BZN) to Beatrice, Nebraska’s Beatrice Municipal Airport (BIE)—was his first in the Skymaster since he’d purchased the aircraft in 2022.

Following an uneventful departure from BZN, the Skymaster climbed to 11,500-feet MSL. Upon encountering a cloud-deck, the pilot descended the aircraft to 9,500-feet. During a subsequent climb back to 11,500-feet, the pilot observed the Skymaster’s aft engine instruments registered an oil-pressure drop and commensurate spike in oil-temperature. As the aircraft was in the vicinity of Laurel Montana’s Laurel Municipal Airport (6S8), the pilot opted to initiate a precautionary landing.

The pilot configured the Skymaster for landing, then shut down the aircraft’s aft engine and secured the propeller thereof.

Approximately one-quarter mile from the approach end of 6S8’s runway 22, the Skymaster lost altitude and airspeed, stalled at an altitude of ten-feet AGL, and impacted a drainage ditch.

The pilot escaped injury. The aircraft did not, and was recovered from the accident-site for further examination.

The accident remains under investigation, ergo the antecedent information is subject to change.

The Cessna Skymaster is an American-built, twin-reciprocating-engine, civil utility aircraft featuring a centerline-thrust architecture comprising forward and aft engines driving tractor and pusher propellers respectively. The aircraft’s pod-style fuselage is slung beneath a semi-cantilever wing from which twin-booms extend to an “H”-tail empennage consisting of twin vertical-stabilizer/rudder assemblies bridged by a fixed horizontal-stabilizer paired with a trailing-edge elevator.

Notwithstanding the 337’s inherent absence of the yawing moments typical of engine-out scenarios in conventional twin-engine aircraft, Skymaster pilots are required by Federal Aviation Regulation to hold multi-engine ratings. Nevertheless, most part 135 and 121 certificate holders—within the context of pilot hiring—do not consider flight-time logged in Cessna 337 models true multi-engine time.

Among the Skymaster’s idiosyncrasies is the tendency of the aft engine to overhead during taxi operations on hot days.

During a 39-year production run spanning 1963 to 1982, Cessna produced 2,993 Skymaster aircraft in no fewer than 14 civil and eight military iterations.

Advanced Aim Mobility (AAM) startups VoltAero and Ampaire vetted proprietary hybrid/electric powertrains utilizing Cessna Skymaster test aircraft.

FMI: www.ntsb.gov