# NTSB CHI01LA075: Enstrom 480, N704G, Dryden, MI, January 25, 2001 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Limited investigation · Final report - Date: January 25, 2001, 18:12 local (23:12 UTC) - Place: Dryden, MI - Coordinates: 42.939201, -83.119606 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=42.9392&lon=-83.1196&mi=10 - Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping) - Highest injury: Serious injuries - Injuries: 1 serious, 2 minor - Status: Completed, report February 20, 2002 - Report: Approved by Office Director - Parties: FAA-Detroit, Michigan FSDO - NTSB case key (mKey): 52064 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI01LA075 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/52064/pdf - Page: https://openairdocs.org/ntsb/CHI01LA075 ## Probable cause The pilots failure to maintain altitude/clearance from the terrain. The dark night was a factor. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - In flight collision with terrain/water, approach - vfr pattern - downwind - light condition - dark night (contributing factor) - altitude/clearance - not maintained, pilot in command (cause) ## Analysis The helicopter was on the downwind leg of an approach to land at the pilot's private heliport. The pilot said, "I took off from my hangar on my farm at about 5:00 pm with 2 friends to just go for a flight local. After flying about 40 minutes in the area of my farm we started back home. The weather was perfect with hardly any wind under 5 knots out of [the] north. I started a southernly downwind to my landing pad. We had just got over a frozen lake in the downwind when without warning or any reason to believe anything was wrong, the helicopter drop[ped] straight down on the lake without me moving any flight controls." A postaccident examination of the helicopter was conducted. The helicopter came to rest about 300 feet from the initial impact point on the frozen lake. No anomalies were found with respect to the airframe that could be associated with a pre-impact condition. No anomalies were found with respect to the engine. The end of civil twilight occured at 1807 and the phase of the moon was a waxing crescent with 1% of the Moon's visible disk illuminated. ## Factual narrative On January 25, 2001, at 1812 eastern standard time, an Enstrom 480 helicopter, N704G, piloted by a private pilot, was substantially damaged on impact with a frozen lake near Dryden, Michigan. The aircraft was on the downwind leg of an approach to land at the pilot's private heliport. The 14 CFR Part 91 flight was not on a flight plan. Visual meteorological conditions prevailed at the time of the accident. The pilot was seriously injured, and the two passengers received minor injuries. The flight originated from the pilots farm about 1700. The pilot said in a written statement, "I took off from my hangar on my farm at about 5:00 pm with 2 friends to just go for a flight local. After flying about 40 minutes in the area of my farm we started back home. The weather was perfect with hardly any wind under 5 knots out of [the] north. I started a southernly downwind to my landing pad. We had just got over a frozen lake in the downwind when without warning or any reason to believe anything was wrong, the helicopter drop[ped] straight down on the lake without me moving any flight controls." A postaccident examination of the helicopter was conducted. The helicopter came to rest on the frozen lake in an upright position with the landing gear collapsed. The helicopter came to rest about 300 feet from the initial impact point. All three main rotor blade spars remained attached to the rotor hub. The main rotor drive rotated freely. The main rotor pitch change links were all separated at the upper rod end. All of the breaks exhibited signatures consistent with overload failure. The control system was examined and the cyclic controls were found to be continuous from the cyclic sticks to the swashplate. The collective control was continuous from the collective sticks to the swashplate except for a rod end bearing at the collective torque tube bellcrank that had separated from the pushrod. The separated collective system pushrod and rod end bearing were examined. The bearing assembly had failed in the threaded portion of the shank. The pushrod was found to have a bend with scuffing on the inside of the bend. A metallurgical examination of the failed portion of the rod end bearing revealed signatures consistent with mechanical overload due to a bending load. No anomalies were found with respect to the airframe that could be associated with a pre-impact condition. No anomalies were found with respect to the engine. According to the United States Naval Observatory internet site, the end of civil twilight occured at 1807 and the phase of the moon was a waxing crescent with 1% of the Moon's visible disk illuminated. ## Aircraft - Registration: [N704G](https://openairdocs.org/deregistered/N704G-2016-12-16), registration cancelled 2016-12-16, S/N 5035 (OpenAirDocs) - Reported make and model: Enstrom 480 - Registry model: [Enstrom Helicopter 480](https://openairdocs.org/model/enstrom-helicopter-480) (registry code 3300560) (OpenAirDocs) - Category: Helicopter - Serial number: 5035 - Airframe hours: 92 - Engines: Rolls-Royce 250-C20W 420 horsepower turbo shaft - Damage: Substantial damage - Flight: Personal, Part 91 - Registered owner: Site Development Services, Inc. - Airworthiness certificate: Standard, Normal - Last inspection: Annual, November 7, 2000, 6 hours before - Departed: PVT, Metamora, MI - Destination: NONE, Dryden, MI ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 50; injuries: serious; private; medical: class 3, valid medical--w/ waivers/lim; last flight review October 15, 2000; seat: left; flight hours: 800 total ## Weather - Conditions: Visual (VMC), Night/dark - Wind: 230° at 4 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 25 °F, dew point 16 °F - Altimeter: 30.30 inHg - Observed at: FNT, 25 nm away ## 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 20010125006619A](https://openairdocs.org/incident/20010125006619A), Jan 25, 2001: Camair 480, Dryden, MI, No damage. (-19) On January 25, 2001, at 1812 EST, an Enstrom 480 helicopter, N704G, piloted by a private pilot, was substantially damaged on impact with a frozen lake… 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.