ASN Wikibase Occurrence # 285932
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| Date: | Tuesday 24 June 2008 |
| Time: | 07:45 LT |
| Type: |  Enstrom 480B |
| Owner/operator: | Enstrom Helicopter Corporation |
| Registration: | N480PD |
| MSN: | 5080 |
| Year of manufacture: | 2005 |
| Total airframe hrs: | 707 hours |
| Engine model: | Rolls Royce 250-C20W |
| Fatalities: | Fatalities: 0 / Occupants: 2 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | MARINETTE, Wisconsin -
 United States of America
|
| Phase: | Manoeuvring (airshow, firefighting, ag.ops.) |
| Nature: | Test |
| Departure airport: | Menominee Marinette Twin County Airport, MI (KMNM) |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
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.
Probable Cause: 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.
Accident investigation:
 |
|
Sources:
NTSB CHI08FA172
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 02-Oct-2022 17:16 | ASN Update Bot | Added |
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