# NTSB CHI94LA022: Hiller UH12E, N4026S, Sioux Rapids, IA, October 22, 1993 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: October 22, 1993, 15:30 local (20:30 UTC) - Place: Sioux Rapids, IA - Coordinates: 42.889141, -95.140396 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=42.8891&lon=-95.1404&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report October 20, 1994 - Report: Approved by Office Director - NTSB case key (mKey): 9418 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI94LA022 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/9418/pdf - Page: https://openairdocs.org/ntsb/CHI94LA022 ## Probable cause the Pilot in Command failed to maintain clearance with the terrain while proceeding up an upslope. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power, maneuvering - aerial application - reason for occurrence undetermined - Forced landing, descent - emergency - Dragged wing,rotor,pod,float or tail/skid, landing - clearance - not maintained, pilot in command (cause) ## Analysis THE PILOT REPORTED HE WAS SPRAYING A PASTURE WHEN THE ENGINE STARTED RUNNING ROUGH. DURING THE FORCED LANDING, THE LEFT SKID MADE CONTACT WITH THE GROUND AND THE HELICOPTER ROLLED TO THE RIGHT AND STRUCK THE GROUND. THE HELICOPTER WAS DESTROYED BY FIRE. POST ACCIDENT INSPECTION DID NOT FIND ANY REASON FOR THE ENGINE POWER LOSS. ## Factual narrative On October 22, 1993, about 1530 central daylight time (CDT), a Hiller UH12E helicopter; N4026S, was destroyed when the left skid hit the ground, and the aircraft caught fire in Sioux Rapids, Iowa. The Aerial application flight, originating from Webb, Iowa, was operating under 14 CFR Part 137 in visual meteorological conditions with no flight plan on file. The commercial certificated helicopter pilot reported he was in the process of spraying a pasture and was traveling north for a pass up a sloping valley when the engine began to run rough and started losing power. Because of the terrain, the pilot decided he could not set the helicopter down at that point and was trying to continue up the hill to flat ground. The aircraft continued to lose power and the left skid made contact with the hillside, yawed to the right, rolled on it's right side and was destroyed by a post-impact, on-ground fire. The pilot escaped without any injury. The pilot stated he had sprayed several loads and had fueled the helicopter several times during the morning of the 22nd. He had not experienced any problems during the morning spraying. After lunch, he fueled the helicopter with about 20 gallons of fuel, conducted a walk around, and drained the carburetor bowl in accordance with the pilot's operating handbook. About 10 minutes into the accident flight, he experienced the power loss. On scene investigation found the platform section 15 feet north and about 3 feet to the right of the initial ground scar. The platform section was laying on its right side with the nose pointed to the west and the main rotor shaft pointing to the north. The tail boom was intact but was twisted 90 degrees clockwise around the longitudinal axis at the seam just forward of the first universal joint of the tail rotor shaft. The spray tank which was mounted on the belly of the platform section had all the attach points broken. The chemical hoses were destroyed by fire and the tank separated from the platform and toppled down the hill approximately 25 feet and burned itself out. The fire that destroyed the helicopter burned an area of the pasture in an arch from about 15 feet west of the platform to 30 feet north of the platform to about 15 feet east of the platform. There is a diagram attached. The Pilot's Aircraft Accident Report was received July 15, 1994, was unsigned and the section "Narrative History of Flight" was not filled in. The lower end of the engine and engine mount was dislodged from its mount. All magnesium parts and a large portion of aluminum parts were melted down. The engine and transmission oil sumps, accessory case, magnetos, carburetor, fuel pumps, cooling fan, portions of engine case, cylinder heads, and portion of the transmission were totally destroyed by the fire. Because of the destruction caused by the fire there was very little documentation of various engine components and engine accessories that could be obtained. Of those controls that were not destroyed by the fire it appeared that they were all attached and safetied properly. The cockpit area and all instrumentation was destroyed. A review of the maintenance records indicate that the aircraft received an annual inspection 09/20/93. In addition to the inspection, various components were replaced on that date with freshly overhauled units including the engine. There were approximately 49 hours accumulated flight time since the overhaul of the engine, major components, and the annual inspection. ## Aircraft - Registration: [N4026S](https://openairdocs.org/deregistered/N4026S-2002-11-04), registration cancelled 2002-11-04, S/N 5055, built 1978 (OpenAirDocs) - Reported make and model: HILLER UH12E - Registry model: [Hiller UH-12E](https://openairdocs.org/model/hiller-uh-12e) (registry code 4360122) (OpenAirDocs) - Registry engine: [Lycoming VO-540 series](https://openairdocs.org/engine/lycoming-vo-540-series) (registry code 41534, reciprocating) (OpenAirDocs) - Category: Helicopter - Serial number: 5055 - Airframe hours: 4547 - Engines: LYCOMING VO-540 C2A 305 horsepower reciprocating - Damage: Destroyed - Fire: On-Ground - Flight: Aerial application, Part 137 - Operator: Jackson, Warren A. - Registered owner: Bonanza Valley Aviation, Inc. - Last inspection: Annual, September 20, 1993, 44 hours before - Departed: NONE, WEBB, IA ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 61; commercial; airplane ratings: single-engine land, multi-engine land; instrument ratings: helicopter; medical: class 2, valid medical--w/ waivers/lim; seat: center; flight hours: 13,875 total, 2,000 in this make and model, 13,540 as pilot in command, 300 in the last 90 days, 100 in the last 30 days, 8 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 210° at 7 knots, gusting 10 - Visibility: 15 statute miles - Lowest ceiling: none - Temperature: 72 °F - Altimeter: 30.00 inHg ## 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 19931022040789A](https://openairdocs.org/incident/19931022040789A), Oct 22, 1993: Hiller UH12E, Sioux Rapids, IA, Destroyed. Rough engine spraying pasture. On forced landing left skid contacted ground. Rolled over and burned. Engine normal. ## Other investigations on N4026S (2) 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 LAX82DA306](https://openairdocs.org/ntsb/LAX82DA306), Aug 20, 1982: Hiller UH-12E (N4026S), Chandler, AZ, substantial damage - [NTSB FTW79FQG05](https://openairdocs.org/ntsb/FTW79FQG05), Oct 19, 1978: Hiller UH-12E (N4026S), Stratford, TX, substantial damage 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.