# Accident 19980520016109A: Hughes 500N, Lanaicity, HI, May 20, 1998 - Type: FAA accident report (Accident/Incident Data System), as reported - Date: May 20, 1998, 05:00 local time - Place: Lanaicity, HI - Damage: Destroyed - Phase of flight: Fcd/Prec Ldg From Cruise - Operating rules: Air taxi and commuter (Part 135) - Operator: WVXA - Location: 20.8303° N, 156.9199° W: From the FAA, an estimate near the named town, within about 3 miles - Nearby events: https://openairdocs.org/map.md?lat=20.8303&lon=-156.9199&mi=10 - Aircraft: N112HD, a cancelled registration (https://openairdocs.org/deregistered/N112HD-1998-10-30) (OpenAirDocs) - Registry model: Mcdonnell Douglas Helicopter 500N (registry code 3027374, https://openairdocs.org/model/mcdonnell-douglas-helicopter-500n) (OpenAirDocs) - Reported make and model: HUGHES 500N - Reported engine: ALLSN 250C20R - People aboard: 4 - Fatal injuries: 0 - Pilot flight hours: 7,221 total, 2,569 in this make and model, 223 in the last 90 days - NTSB investigation: [NTSB LAX98LA166](https://openairdocs.org/ntsb/LAX98LA166) (OpenAirDocs) - FAA source: FAA Aviation Safety Information Portal (https://asip.faa.gov/) - Page: https://openairdocs.org/incident/19980520016109A ## Narrative As the FAA filed it, in capitals; the FAA replaces private details with ^PRIVACY DATA OMITTED^. (.19) ON MAY 20, 1998, AT 0500 HOURS HAWAIIAN STANDARD TIME, A MCDONNELL-DOUGLAS 500N, N112HD, EXPERIENCED AN UNCONTAINED ENGINE FAILURE DURING CRUISE AND MADE AN EMERGENCY LANDING IN ROUGH TERRAIN, 5 MILES NORTH OF LANAI CITY, HAWAII. THE HELICOPTER WAS SUBSEQUENTLY DESTROYED IN A POSTIMPACT FIRE. THE HELICOPTER, OPERATED BY WINDWARD AVIATION INC., UNDER 14 CFR PART 135, WAS CHARTERED BY THE MAUI POLICE DEPARTMENT. THE COMMERCIAL RATED HELICOPTER PILOT AND THREE MAUI POLICE DEPARTMENT OFFICERS WERE NOT INJURED. VISUAL METEOROLOGICAL CONDITIONS EXISTED FOR THE FLIGHT AND NO FLIGHT PLAN WAS FILED. THE PILOT REPORTED THAT AT APPROXIMATELY 500 TO 600 FEET ABOVE GROUND LEVEL (AGL) THE ENGINE CHIP LIGHT ILLUMINATED. APPROXIMATELY 10 SECONDS LATER, THE ENGINE-OUT LIGHT FLICKERED AND THEN FULLY ILLUMINATED. THE PILOT STATED THAT AS HE PERFORMED AN AUTOROTATION HE HEARD A LOUD "BANG." ACCORDING TO AN FEDERAL AVIATION ADMINISTRATION INSPECTOR FROM THE HONOLULU FLIGHT STANDARDS DISTRICT OFFICE, LARGE HOLES WERE FOUND IN THE MAIN ROTOR BLADES. THE INSPECTOR ALSO NOTED THAT THE BLADES FROM THE NUMBER THREE AND FOUR TURBINE WHEELS WERE MISSING. (.4)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 OT THE POWER TURBINE ROTOR TO LOSS OF POWER TURBINE GEAR TRAIN ENGAGEMENT. METAL DEBRIS WAS INCASED ON THE TIP OF ONE OD THE CHIP DETECTORS. THE OIL DELIVERY TUBE THAT SUPPLIES OIL TO THE NO. 5 BEARING WAS NOT RECOVERED AND WAS ASSUMED TO HAVE CONSUMED IN THE POSTIMPATCH FIRE. (-23) WHILE CONDUCTING A NIGHT FAR 135 FLIGHT, AT 600 FEET AGL, THE PILOT RECEIVED AN ENGINE CHIP LIGHT WITH AN ENGINE OUT AUDIBLE AND INITIATED AN AUTOROTATION. DURING THE AUTOROTATION THE HELICOPTER EXPERIENCED AN UNCONTAINED ENGINE FAILURE OF THE NUMBER 3 AND 5 TURBINE WHEELS. THE HELICOPTER LANDED, ROLLED ONTO ITS RIGHT SIDE AND WAS CONSUMED BY A POST FIRE. ## The NTSB's investigation of this event (1) From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. - [NTSB LAX98LA166](https://openairdocs.org/ntsb/LAX98LA166), May 20, 1998: McDonnell Douglas 520N (N112HD), Lanai City,Maui, HI, destroyed. Probable cause: An oil starvation failure of the number 5 bearing for undetermined reasons. From the FAA Accident/Incident Data System. Reports are matched to registry aircraft by N-number and event date, checked against the reported make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. For accidents, the NTSB's own investigation is the fuller record. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.