# NTSB CHI98LA171: Stemme S10V, N97MT, Plymouth, WI, May 19, 1998 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: May 19, 1998, 14:45 local (19:45 UTC) - Place: Plymouth, WI - Coordinates: 43.739803, -87.969665 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=43.7398&lon=-87.9697&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report February 15, 2001 - Report: Approved by Office Director - NTSB case key (mKey): 10889 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI98LA171 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/10889/pdf - Page: https://openairdocs.org/ntsb/CHI98LA171 ## Probable cause the improper in-flight decision of the pilot in command to initiate a turn at a close proximity to the ground. Factors to the accident were the starting procedures not being followed and the inadequate altitude to initiate the engine restart. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Miscellaneous/other, descent - normal - starting procedure - not followed, pilot in command (contributing factor) - altitude - inadequate, pilot in command (contributing factor) - Forced landing, descent - normal - Dragged wing,rotor,pod,float or tail/skid, maneuvering - turn to landing area (emergency) - in-flight planning/decision - improper, pilot in command (cause) - In flight collision with terrain/water, descent - uncontrolled ## Analysis At an altitude of 1000 feet above ground level (agl) the pilot started the transition between soaring mode and powered flight mode. When completed the pilot observed that throttle movements did not produce power changes. The pilot said he picked a field for an off-airport landing and initiated a normal gliding approach to the field. Between 100 and 150 feet of the off-field landing site the pilot decided to turn into the wind, which was at a 45-degree crosswind, and the left wing tip contacted the ground in a 20-degree bank. The aircraft has a 75.5' wing span. Post accident investigation showed that there was usable fuel in both of the wing tanks. The engine and the drive train were undamaged from the accident. A test run of the engine showed that the engine started, without hesitation, and throttle response was determined to be normal. Engine controls and indications appeared to be in the normal operation limits. No other discrepancies were found. ## Factual narrative On May 19, 1998, at 1445 central daylight time, a Stemme S10V, N97MT, piloted by commercial pilot, sustained substantial damage when it impacted the terrain during an off-airport landing. The commercial pilot was unable to transition the motor glider from soaring mode to powered flight mode. Visual meteorological conditions prevailed at the time of the accident. The 14 CFR Part 91 pleasure flight was not operating on a flight plan. The pilot and one passenger reported no injuries. The local flight departed Sheboygan County Memorial Airport, Sheboygan, Wisconsin, at 1245. According to the pilot's written statement, he was trying to locate sustaining lift over the Kettle Moraine front hills when it became evident that the aircraft had insufficient glide altitude to make the predetermined landing area. The pilot indicated that this decision was made around 1000 feet above ground level (agl). The pilot initiated the engine restart sequence, but when completed noticed that throttle movements did not produce power changes. The pilot stated he checked both fuel selectors for correct position, checked that the fuel pump & emergency fuel pump were on, and finally reactivated the nose cone opening lever. The pilot said he picked a field for an off-airport landing and initiated a normal gliding approach to the field. The pilot stated in a telephone conversation, with the Investigator-In-Charge (IIC), "Between 100 and 150 feet of the off-field landing site I decided to turn into the wind, which was at a 45-degree crosswind, and the left wing tip contacted the ground in a 20-degree bank." The pilot stated that the aircraft has a 75.5' wing span. According to a written statement from an inspector with the Federal Aviation Administration (FAA), the pilot stated that he didn't believe the engine was developing power at the time of the accident. Furthermore the pilot stated that, "he attempted to alter his landing course at too low of an altitude which resulted in the left wing contacting the ground and the subsequent aircraft breakup." The pilot also made the statement that 1000' agl was probably too low of an altitude to safely initiate the engine restart. Post accident investigation showed that there was usable fuel in both of the wing tanks. The engine and the drive train were undamaged from the accident. Both propeller blades were removed to facilitate a test run of the engine. The test run showed that the engine started, without hesitation, and throttle response was determined to be normal. Engine controls and indications appeared to be in the normal operation limits. No other discrepancies were found. ## Aircraft - Registration: [N97MT](https://openairdocs.org/aircraft/N97MT), registered now, S/N 14-042M, built 1992 (OpenAirDocs) - Reported make and model: Stemme S10V - Registry model: [Stemme S10-V](https://openairdocs.org/model/stemme-s10-v) (registry code 1130871) (OpenAirDocs) - Registry engine: [NONE](https://openairdocs.org/engine/none) (registry code 00000, none) (OpenAirDocs) - Category: Unknown - Serial number: 14--042M - Airframe hours: 714 - Engines: Limbach L2400/ EB1.AD 93 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Registered owner: Terry J. Kohler - Airworthiness certificate: Standard, Normal - Last inspection: Annual, December 10, 1997, 6 hours before - Departed: SBM, SHEBOYGAN, WI ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 64; commercial; airplane ratings: multi-engine sea, single-engine sea, single-engine land, multi-engine land; instrument ratings: helicopter; medical: class 2, valid medical--w/ waivers/lim; seat: left; flight hours: 7,000 as pilot in command, 40 in the last 90 days, 6 in the last 30 days, 4 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 250° at 11 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 82 °F, dew point 61 °F - Altimeter: 29.00 inHg - Observed at: SBM, 9 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 19980519010309A](https://openairdocs.org/incident/19980519010309A), May 19, 1998: Stemme S10, Plymouth, WI, Substantial damage. Acft exper engine problems and made an emerg landing in a plowed field, fuselage broke behind the engine, (.4)at an altitude of 1000 feet above ground level… 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.