Enstrom 480B N480PD

Summary

On 24 June 2008 at about 13:45 local time, a Enstrom 480B registered N480PD, operated by Enstrom Helicopter Corporation, was involved in an accident near Marinette, Wisconsin, United States. 2 people were on board and nobody was injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

24 June 2008 at 13:45

Classification

Accident

Location

Marinette, Wisconsin, United States

Coordinates

45.0806, -87.6204

Aircraft

Enstrom 480B

Registration

N480PD

Category

Helicopter

Engines

1

Operator

Enstrom Helicopter Corporation

Operating rule

Part 91: General Aviation

Purpose of flight

Flight Test

Phase of flight

Not recorded

Route

Menominee → Unknown

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

CHI08FA172

Nobody was injured.

The pilot inadvertently operating the helicopter at a gross weight greater than its maximum allowable operating weight, and flying the helicopter at an airspeed greater than the never-to-exceed speed for the helicopter’s gross weight condition, resulting in structural damage to the tailcone.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

The purpose of the test flight was to determine performance characteristics of the manufacturing company's helicopter at maximum gross weight and maximum aft center of gravity (CG). The helicopter was in a climb at 95 knots indicated airspeed and the pilot had just applied power when he and his passenger noticed a moderate to severe vibration which lasted a few seconds. The pilot reduced power and it went away. The pilot then reduced power to around 55 psi torque at about 90 knots indicated airspeed and trimmed forward to do a reverse trim check while trying to maintain torque and altitude with slightly heavy collective. Then there was a shudder, followed almost instantly by a loud bang and crunching sound, before the nose pitched down and the helicopter turned 120 to 150 degrees to the left. The pilot regained control, selected a field, and proceeded to make an emergency landing. As he began his landing, he noted he no longer had pedal control. The pilot added throttle, managed to bring the nose around, and landed the helicopter straight ahead. Postaccident inspection of the helicopter revealed that the tailcone was buckled in front of the horizontal stabilizer, displacing the stabilizer trailing edge downward and causing slack in the tail rotor control cables. No other preimpact anomalies were found with the helicopter or its systems. Further examination determined that before the flight they had put more fuel in the helicopter than was indicated on the fuel gauges. This resulted in the helicopter being operated at a higher-than-maximum gross weight, at its aft most CG, and reduced the helicopter's never-to-exceed airspeed (Vne) to 87 knots indicated airspeed. When the pilot exceeded Vne during the climb, structural damage occurred.

Quoted verbatim from the NTSB record.