Hard landing causes landing gear failure in Piper J3C

Casualties unknown • Diemtigen, BE, CH

A private flight to Diemtigen ended in a heavy landing and landing gear collapse after the pilot misjudged the approach to an unprepared field.

What happened

On September 8, 1972, a Piper J3C, registration HB-ODZ, was conducting a private VFR flight to an unprepared landing site near Diemtigen, Switzerland. The pilot, accompanied by an avalanche specialist, was traveling from Kägiswil to inspect a potential site for a new ski lift installation. To prepare for the landing, the pilot had previously scouted the meadow and performed several practice landings on the site.

During the approach, the pilot flew over the landing area to observe wind conditions, which were noted as light and variable. The pilot initiated a right-hand turn into the final approach approximately 500 meters from the intended touchdown point. While descending with the engine at idle, the aircraft struck the sloping terrain roughly 15 meters short of the target area. The impact was severe, causing the aircraft to bounce before the right main landing gear collapsed. The Piper J3C came to a rest on its fuselage. There were one fatality and one injury recorded among the occupants.

The investigation

The investigation examined the aircraft's airworthiness, the pilot's credentials, and the mechanical state of the landing gear. The aircraft was found to be airworthy, with weight and balance within limits. While the airspeed indicator was found to be under-reporting speeds between 80 km/h and 130 km/h by approximately 2 to 4 km/h, this was not deemed a primary cause.

Technical analysis of the landing gear revealed that the main gear bracket failed due to impact forces. Microscopic examination of the central tube in the landing gear suspension showed signs of failure due to exceeding tensile strength. The investigation also considered whether previous training flights might have already caused structural deformation to the suspension tube.

Findings

The pilot misjudged the altitude and distance required for the approach to the landing site.
The pilot utilized an inappropriate landing tactic relative to the rising terrain.
The aircraft struck the ground too early due to an undershot approach.
The landing gear failure was a result of the high-impact force of the hard landing.

Probable cause

The accident was caused by the pilot approaching the landing site too low and using an unsuitable landing technique, resulting in a premature impact on the rising terrain.

Frequently asked questions

What happened in the 1972-09-07 PIPER AIRCRAFT CORPORATION J3C-65/L-4. accident near Diemtigen, BE, CH?

A private flight to Diemtigen ended in a heavy landing and landing gear collapse after the pilot misjudged the approach to an unprepared field.

What aircraft was involved and where did it happen?

The accident on 1972-09-07 involved a PIPER AIRCRAFT CORPORATION J3C-65/L-4., registration HB-ODZ, at Diemtigen, BE, CH.

What was the probable cause of the accident?

The accident was caused by the pilot approaching the landing site too low and using an unsuitable landing technique, resulting in a premature impact on the rising terrain.

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