Cessna 152 N48440 accident near Hillsboro, Oregon

Probable cause

The student pilot's improper pitch control during the landing flare, which resulted in a porpoise and substantial damage to the engine mount.

NTSB analysis

The student pilot reported that during a short field landing, she flared a "little bit too high". She pushed the yoke forward, and the nose wheel impacted the ground first, subsequently the airplane porpoised and impacted a taxiway edge identifier light on the edge of the runway. The student pilot further reported that after she applied "heavy" brakes she taxied the airplane to the ramp area without further incident.

The airplane sustained substantial damage to the engine mount.

According to the student pilot there were no preimpact mechanical failures or malfunctions with the airframe or engine that would have precluded normal operation.

The Federal Aviation Administration has published the Airplane Flying Handbook FAA-H-8083-3A (2004). This handbook discusses porpoising and states in part:

In a bounced landing that is improperly recovered, the airplane comes in nose first setting off a series of motions that imitate the jumps and dives of a porpoise—hence the name. The problem is improper airplane attitude at touchdown, sometimes caused by inattention, not knowing where the ground is, mistrimming or forcing the airplane onto the runway.

Ground effect decreases elevator control effectiveness and increases the effort required to raise the nose. Not enough elevator or stabilator trim can result in a nose low contact with the runway and a porpoise develops.

Porpoising can also be caused by improper airspeed control. Usually, if an approach is too fast, the airplane floats and the pilot tries to force it on the runway when the airplane still wants to fly. A gust of wind, a bump in the runway, or even a slight tug on the control wheel will send the air plane aloft again.

The corrective action for a porpoise is the same as for a bounce and similarly depends on its severity. When it is very slight and there is no extreme change in the airplane's pitch attitude, a follow-up landing may be executed by applying sufficient power to cushion the subsequent touchdown, and smoothly adjusting the pitch to the proper touchdown attitude.

Text from the NTSB. Open the NTSB docket for GAA16CA431 for the full record.