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Porpoises & wheel barrows

 

The airport FSS staff observed the arrival and landing of a Cessna 182 as very rough and the aircraft porpoised several times. Objects were observed to be departing the aircraft. The pilot elected to abort the landing and go around after the third bounce. The aircraft landed safely on the second attempt.

Maintenance advised that the damage included a propeller strike requiring the prop being replaced and the engine being torn down, inspected and repaired. The engine firewall, the lower fuselage pans and area skins all required replacement. The nose gear and engine mounts required repair and the main landing gear and airframe were given a hard landing inspection.

The pilot of a Cessna 152 conducting a touch-and-go applied power for the take-off before the flaps were retracted. The aircraft became airborne sooner than expected by the pilot, so he retarded the power to abort the take-off. The nose wheel contacted the runway first and the aircraft began to porpoise. The aircraft sustained a blown nose wheel tire and damage to the firewall at the nose landing gear mount.

A porpoise usually occurs when the aircraft is landed hard, bounces and the pilot tries to push it back onto the ground. The nose wheel strikes the ground next, then the main wheels, then the nose, then the mains, etc. Serious damage to the nose gear may occur any time after the third time the nose strikes the runway, and as can be seen from the incident related above, other damage may occur.

The only recovery from a porpoise is to raise the nose, add full power and abort the landing. The C-152 pilot may have made the right decision to not attempt a go around after the porpoise started due to the position of his flaps.

Porpoising Fig. 1

Any attempt to salvage a landing usually results in the collapse of the nose wheel and a prop strike. The porpoise happens rapidly. When the pilot realizes the nose is coming down and he/she pulls back on the control column the nose will have already hit the ground and the pilot has made the situation worse. Control movements will be one step behind what is required.

WHEEL BARROWING

A Mooney M20C was on approach to the airport when the Tower Controller

advised the pilot to land long and exit the runway without delay. The pilot did land long, but with excess airspeed and then he tried to hold the aircraft on the ground. The aircraft wheel barrowed and the prop struck the runway.

Wheel barrowing may occur anytime a pilot tries to force the aircraft onto the ground and hold it there when the airspeed is too high. The weight of the aircraft is primarily on the nose wheel, reducing directional control, and since little of the aircraft weight is on the main wheels, there is little braking action. Wheel barrowing may result in a loss of control.

Wheel barrowing may also occur when a pilot tries to hold the aircraft on the ground after take-off speed has been reached. The weight of the aircraft is transferred to the nose wheel resulting in poor directional control or a loss of directional control.

If you think wheel barrowing is occurring during a landing, pull back on the control column to get the aircraft weight off the nose and onto the main wheels. If too much runway has gone by, add full power and abort the landing. If on take-off, pull back and fly away.

Wheel Barrowing Fig. 2

Fig.3 shows the length of the arm between the main wheels and the vertical stabilizer/rudder. Any application of rudder on the ground forces a turn around inside the main wheel. The arm between the nose wheel and the vertical stabilizer is much longer and during a wheel barrow, the single nose wheel is the pivot point. Even the slightest movement of the rudder will result in a large change of direction.

Arm from nose wheel to vertical stabilizer

Arm from Arm from main

nose wheel wheels to vertical

to main wheels stabilizer

Fig. 3

An attempt to salvage a poor approach and landing can result in either of these scenarios. Do not let yourself be talked into doing something that may get you into trouble. Landing long is fine if everything is under control. If you don’t like what is happening, go around. You are flying the airplane, not the controller.

Dale Nielsen is an ex-Armed Forces pilot and aerial photography pilot. He lives in Abbotsford, B.C., and currently flies air charters. He still freelances as a flying instructor and seminar facilitator. Nielsen is also the author of seven flight training manuals published by Canuck West Holdings.

Got an aviation safety story to tell? Dale Nielsen would like to hear from pilots who have educational aviation experiences to relate. Excerpts from these stories will be used in upcoming safety articles. Dale can be contacted via e-mail: dale@flighttrainingmanuals.com