Enstrom Helicopter CORP 480B accident near Marinette, Wisconsin, June 24, 2008
On June 24, 2008 at about 1:45 pm local time, a Enstrom Helicopter CORP 480B, registered N480PD, was substantially damaged in an accident during maneuvering near Marinette, Wisconsin. It was a flight test under general aviation rules (Part 91). No one was hurt; 2 people were on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
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.
Source: NTSB aviation accident database, copy made October 4, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- June 24, 2008 · about 1:45 pm local time
- Place
- Marinette, Wisconsin · map
- Type
- Accident
- Injuries
- No one was hurt; 2 people were on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Enstrom Helicopter CORP 480B · all 480Bs on the register
- Registration
- N480PD · no longer on the register · serial 5080
- Damage
- Substantial damage
- Flight
- Flight test · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
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.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record from the NTSB's investigation tables, in plain English
What happened, in order
- Abrupt maneuver during maneuvering
- Sys/Comp malf/fail (non-power) during maneuvering defining event
The NTSB's findings
- cause Aircraft › Aircraft oper/perf/capability › Performance/control parameters › Airspeed › Capability exceeded
- Aircraft › Aircraft structures › Empennage structure › (general) › Capability exceeded
Pilot
- Certificate: commercial pilot
- Ratings: single-engine land; instrument: helicopter; rotorcraft: helicopter
- Flight time: 7,409 hours in all; 673 in this make and model; 109 in the last 90 days; 29 in the last 30 days; 6,730 as pilot in command
- Last flight review: March 20, 2007
- Medical certificate: Class 2 (with waivers/limitations)
- Seat: left
- Injury: no injuries
The aircraft
- Airframe total time: 707 hours
- Last inspection: 100-hour inspection, March 28, 2008
- Maximum gross weight: 3,000 lb
- Seats: 3
- Landing gear: fixed
- Engine: Rolls-Royc 250-C20W (turboshaft); 0 hours total
- Operator: Enstrom Helicopter Corporation
The flight
- Departed from: MNM Menominee MI at 5:00 am
Weather at the time
- Light: daylight
- Wind: from 200° at 4 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 63°F (17°C), dew point 0°F (-18°C)
- Altimeter: 30.15 inHg
- Observation at 12:55 pm from KMNM, 5 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 | |||
| Passengers | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
The docket, the folder of records gathered during an investigation (maintenance records, photographs, witness statements, examinations), has not been read from the NTSB for this case yet; the list appears here once it has. Open the docket at the NTSB.
About this page
Everything above comes from the NTSB's public accident database: the narrative, probable cause and findings are the NTSB's own words, and the coded tables behind its report (pilot, aircraft, flight, weather, injuries, sequence of events) are written out in plain English. Pilots' ages, home towns and medical details are left out on purpose. The documents and photographs are the NTSB's docket, the folder of records gathered during the investigation, shown as the NTSB released them (the NTSB redacts some personal details first) and listed under the NTSB's own titles. This site's own text never names pilots, passengers or anyone else involved. A preliminary report describes what is known soon after the event and can change; the final report, with the probable cause, usually follows one to two years later and this page is refreshed when it does. Case number CHI08FA172.