EDGEWOOD, NM, USA
N99MH
Cessna 337
During climbout after takeoff, the rear engine lost partial power (1,700 rpm). The pilot started to turn around and return to the airpark, but changed his mind and decided to maintain aircraft control by landing in a rough and uneven but open field. Postaccident examination disclosed the safety wire securing the propeller control cable to the support bracket had broken, allowing the cable housing to flex within the engine compartment. When the pilot reduced rpm to climb power, the safety wire broke. This prevented the pilot from feathering or changing the rear propeller pitch settings.
On August 15, 1999, approximately 0920 mountain daylight time, a Cessna 337, N99MH, was substantially damaged when it collided with terrain during a forced landing near Edgewood, New Mexico. The commercial pilot and his passenger were not injured. Visual meteorological conditions prevailed, and no flight plan had been filed for the personal flight being conducted under Title 14 CFR Part 91. The flight had originated just minutes before the accident with an intended destination of Belen, New Mexico. According to the pilot's accident report, during the climbout after takeoff from Sandia Airpark Estates East, the rear engine lost partial power. The pilot turned back towards the airpark, then changed his mind and decided to maintain aircraft control by landing in a rough and uneven but open field. An FAA airworthiness inspector examined the airplane and found that the safety wire securing the propeller control cable to the support bracket had broken, allowing the cable housing to flex within the engine compartment. The inspector wrote, "It appears the broken safety wire allowed the prop[eller] control cable to flex when the RPM was reduced following takeoff, preventing normal operation of the prop[eller] governor and subsequent inability to feather or advance the rear prop[eller] pitch settings." The pilot submitted weight and balance documents indicating that at the time of the accident, the airplane's weight was 3,717 pounds (4,200 pounds maximum gross weight), and that the center of gravity, based on 519,100 pound-inches, was within limits. The following is an excerpt from the 1965 Cessna [337] Super Skymaster Owner's Handbook: "There is no minimum single-engine control speed [for centerline thrust airplanes]. The most critical time for an engine failure in a twin-engine airplane is a two or three-second period late in the takeoff while the airplane is accelerating to the single-engine best rate-of-climb speed. The airplane's climb performance in the event of an engine-out is at the optimum at the best single-engine rate-of-climb speed. This speed is approximately 90 KIAS (knots indicated airspeed) with gear and flaps retracted. Although 90 KIAS is the preferred speed, 80 KIAS may be used with obstacles immediately ahead." There are no performance charts available to predict performance based on one engine developing partial power with its propeller not feathered.
Breakage of the safety wire that secured the propeller control cable to the support bracket. Factors were the inability of the pilot to feather the propeller or change propeller rpm, and rough, uneven, and unsuitable terrain on which to make a forced landing.
Source: NTSB Aviation Accident Database
Aviation Accidents App
In-Depth Access to Aviation Accident Reports
