Mcdonnell Douglas 520N accident near Lanai City,Maui, Hawaii, May 20, 1998
On May 20, 1998 at about 3:00 pm local time, a Mcdonnell Douglas 520N (helicopter), registered N112HD, was destroyed in an accident near Lanai City,Maui, Hawaii. It was a flight of an unrecorded kind under charter and air-taxi rules (Part 135). 1 person had minor injuries; 4 others were unhurt. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
An oil starvation failure of the number 5 bearing for undetermined reasons.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- May 20, 1998 · about 3:00 pm local time
- Place
- Lanai City,Maui, Hawaii · map
- Type
- Accident
- Injuries
- 1 person had minor injuries; 4 others were unhurt.
- Weather
- visual conditions (good weather)
- Aircraft
- Mcdonnell Douglas 520N
- Registration
- N112HD · registry record · serial LN008
- Damage
- Destroyed
- Flight
- Flight of an unrecorded kind · charter and air-taxi rules (Part 135)
The NTSB's narrative final · quoted from the NTSB record
The engine chip light illuminated during cruise and about 10 seconds later the engine out light flickered and then fully illuminated. As the pilot was performing an autorotation he and his passengers heard a loud bang, the helicopter landed on uneven terrain, and subsequently rolled over onto its side. A postcrash fire consumed the helicopter. The third turbine wheel was not located. The fourth turbine wheel was found remote from the helicopter with missing airfoils. In the 5 months prior to the accident, the power turbine had been removed for inspection and repaired several times due to one instance of an N2 lockup and chipped drive splines, and several instances of engine chip light illuminations with high temperatures and turbine rub. In each case, the plugs were removed, inspected per the manufacturer's maintenance manuals, and the oil system flushed. The day before the accident the engine chip light illuminated and the operator found a pasty substance on the chip detector. The chip detector was inspected in accordance with the manufacturer's maintenance manuals and the helicopter was then returned to service. Postaccident disassembly of the engine revealed an oil starvation failure of the No. 5 bearing and a subsequent failure of the No. 3 bearing due to a transfer of the axial loads normally carried by the No. 5 bearing. After the loss of the No. 5 bearing, there was an uncontained overspeed failure of the power turbine rotor to loss of power turbine gear train tooth engagement. Metal debris was encased on the tip of one of the chip detectors. The oil delivery tube that supplies oil to the No. 5 bearing was not recovered and was assumed to have been consumed in the postimpact fire.
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
Pilot
- Certificate: flight instructor, commercial pilot
- Ratings: instructor: helicopter; rotorcraft: helicopter
- Flight time: 7,221 hours in all; 2,569 in this make and model; 223 in the last 90 days; 79 in the last 30 days; 7,221 as pilot in command; 900 on instruments
- Medical certificate: Class 2 (valid medical--w/ waivers/lim.)
- Seat: left
The aircraft
- Airframe total time: 3,861 hours
- Last inspection: 100-hour inspection, May 7, 1998; 19 hours since
- Maximum gross weight: 3,350 lb
- Seats: 5
- Landing gear: fixed
- Engine: Allison 250-C20R (turboshaft); 0 hours total
The flight
- Departed from: OGG Maui HI at 2:35 pm
- Destination: LNY Lanai City HI
- Runway 0
Weather at the time
- Light: night, dark
- Wind: from 060° at 15 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 0°F (-18°C), dew point 0°F (-18°C)
- Observation at 3:00 pm from LNY, 5 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 1 | |||
| Passengers | 1 | 3 |
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.
Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.