# NTSB LAX98LA021: Revolution MINI-500, N7234Y, Long Beach, CA, October 26, 1997 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Limited investigation · Final report - Date: October 26, 1997, 12:33 local (20:33 UTC) - Place: Long Beach, CA - Coordinates: 33.800769, -118.350608 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=33.8008&lon=-118.3506&mi=10 - Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping) - Highest injury: Serious injuries - Injuries: 1 serious - Status: Completed, report May 29, 1998 - Report: Approved by Office Director - NTSB case key (mKey): 29985 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX98LA021 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/29985/pdf - Page: https://openairdocs.org/ntsb/LAX98LA021 ## Probable cause loss of engine power and low rotor rpm for undeterminted reasons. The factory representative's recommendation to reduce the main rotor low pitch stop (from -1.8 degree to -0.5 degree) may have been a related factor. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power, takeoff - initial climb - reason for occurrence undetermined (cause) - Forced landing, emergency descent/landing - autorotation - performed, pilot in command - Hard landing, emergency landing after takeoff - rotor rpm - low (cause) - maintenance,adjustment - reduced, kit manufacturer (contributing factor) ## Analysis After taking off, the helicopter had climbed about 250 to 300 feet, when the engine abruptly lost power. The pilot attempted an autorotation, but said he was able to maintain only 80 percent rotor rpm, which was insufficient to prevent a hard landing. The pilot reported that the main rotor low pitch stop had recently been changed from -1.8 degree to -0.5 degree, as recommended by a factory representative. Also, the pilot stated that he was aware of a phenomenon called 'cold-freeze' (engine seizure without over temp) that (according to him) had occurred with other engines of this make/modle. He believed there was a possible engine seizure and that reduced settings of the rotor low pitch stops could have resulted in low rotor rpm. No preimpact mechanical problem was found that would have resulted in loss of engine power. ## Factual narrative On October 26, 1997, at 1233 hours Pacific standard time, a Revolution Mini-500 experimental helicopter, N7234Y, was destroyed and the commercial pilot seriously injured when it impacted terrain following takeoff at Daugherty Field, Long Beach, California. The aircraft had completed one circuit of the helicopter traffic pattern and landed on Helo Pad 3. It was then cleared for a second circuit of the helicopter traffic pattern. The pilot stated that on the second takeoff, the engine quit abruptly at an altitude of 250-300 feet agl. He then attempted an autorotation, but could get only 80 percent rotor rpm which was insufficient to prevent a hard touchdown. (The pilot stated in his report that he felt this was due to a recent change in the main rotor low pitch stop from -1.8 deg. to -0.5 deg. which had been recommended by a factory representative.) The pilot also stated that he was aware of a phenomenon called "cold-freeze" (engine seizure without over temp) that had happened several times with the Rotax engine. He felt that a possible engine seizure, combined with the change in the rotor low pitch stop, were contributing factors to the accident rather than fuel starvation or mechanical malfunction of the helicopter. ## Aircraft - Registration: [N7234Y](https://openairdocs.org/deregistered/N7234Y-2000-01-29), registration cancelled 2000-01-29, S/N 231 (OpenAirDocs) - Reported make and model: Revolution MINI-500 - Registry model: [Revolution Helicopter MINI-500](https://openairdocs.org/model/revolution-helicopter-mini-500) (registry code 05604CZ) (OpenAirDocs) - Category: Helicopter, amateur-built - Serial number: 231 - Airframe hours: 55 - Engines: Bombardier ROTAX 582 67 horsepower reciprocating - Damage: Destroyed - Flight: Personal, Part 91 - Registered owner: Thomas J. Kardos - Airworthiness certificate: Special, Experimental (Special) - Last inspection: Annual, June 10, 1997, 8 hours before - Departed: LGB - Airport: LGB, Daugherty Field ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 40; commercial; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 2, valid medical--no waivers/lim.; seat: center; flight hours: 504 total, 52 in this make and model, 398 as pilot in command, 37 in the last 90 days, 12 in the last 30 days, 1 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 320° at 6 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 81 °F, dew point 30 °F - Altimeter: 29.00 inHg - Observed at: LGB ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Accident 19971026030989A](https://openairdocs.org/incident/19971026030989A), Oct 26, 1997: Amtr MINI500, Long Beach, CA, Destroyed. Engine failure at 250FT AGL. Autorotated but could only get 80 percent rotor RPM. Possible rotor low pitch stops. 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. --- 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.