# NTSB NYC99LA065: Stinson 108-3, N6191M, Bristol, CT, February 21, 1999 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: February 21, 1999, 11:58 local (16:58 UTC) - Place: Bristol, CT - Location: 41.6816° N, 72.9407° W: Placed by OpenAirDocs: center of Bristol, CT, within about 6 miles (OpenAirDocs) - Nearby events: https://openairdocs.org/map.md?lat=41.6816&lon=-72.9407&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report August 10, 2000 - Report: Approved by Office Director - NTSB case key (mKey): 45838 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=NYC99LA065 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/45838/pdf - Page: https://openairdocs.org/ntsb/NYC99LA065 ## Probable cause The partial loss of power due to the failure of a fatigued connecting rod bolt. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power(partial) - mech failure/malf, cruise - normal - engine assembly,connecting rod bolt - fatigue (cause) - Forced landing, descent - emergency - On ground/water collision with object, landing - roll - object - tree(s) ## Analysis The pilot stated that he heard a loud noise accompanied by a loss of engine power. A forced landing was executed to a field. Inspection of the engine after the accident revealed two holes in the top of the engine crankcase. The number 3 piston, and it's connecting rod and bolts, were removed from the engine and examined. One of the connecting rod bolts contained microfissures typical of fatigue cracking on the head portion of the bolt. The fatigue cracking had initiated from multiple locations on one side of the underhead radius, and had propagated nearly all of the way through the cross section of the bolt before final separation. A review of the Airplane Engine logbooks revealed that the last Major overhaul was conducted on March 3, 1965. ## Factual narrative On February 21, 1999, about 1158 Eastern Standard Time, a Stinson 108-3, N6191M, was substantially damaged when it impacted the ground during a forced landing near Bristol, Connecticut. The certificated private pilot was not injured. Visual meteorological conditions prevailed, and no flight plan was filed for the personal flight conducted under 14 CFR Part 91. The pilot stated he had just terminated communications and radar services from the Bradley Windsor Locks TRACON, when he heard a loud noise accompanied by a loss of power. The pilot began a left-hand turn to search for a place to land. The pilot then transmitted to the radar controller that he was declaring an emergency and landing the airplane into a field. The field had an approximate length of 1,000 feet. As the airplane approached the field heading north, the pilot shut the engine down and was unable to slow the airspeed enough to make a landing at the beginning of the field. Approximately 400 feet from a tree line at the end of the field, the main wheels touched down and the pilot applied braking. Due to the excessive speed the airplane was light on it's wheels and the brakes were ineffective. The pilot attempted to turn to the left to avoid the tree line, but struck three small trees. The airplane came to rest in an upright position facing east. An inspection of the engine by the Federal Aviation Administration revealed two holes in the top of the engine crankcase. The engine was retained, and examined on March 12, 1999. The number 3 and 4 cylinders were damaged extensively, and removed from the crankcase. The Number 3 piston and connecting rod were found separated from the crankshaft. The connecting rod bolts were found in the oil sump pan. The number four piston and connecting rod remained connected to the crankshaft, and exhibited metal pinging on the piston skirt and rod. The connecting rod bolts were attached to the rod. The number 3 piston, and it's connecting rod and bolts, were forwarded to the National Transportation Safety Board Materials Laboratory, Washington, DC, for examination. According to the Metallurgist's Factual Report, one of the connecting rod bolts contained microfissures typical of fatigue cracking on the head portion of the bolt. The fatigue cracking initiated from multiple locations on one side of the underhead radius, and had propagated nearly all of the way through the cross section of the bolt before final separation. A review of the Airplane Engine logbooks revealed that the last Major overhaul was conducted on March 3, 1965, with a recorded total time of 1,612 hours. The pilot reported a total airframe time of 2,593 hours at the time of the accident. ## Aircraft - Registration: [N6191M](https://openairdocs.org/deregistered/N6191M-2013-04-26), registration cancelled 2013-04-26, S/N 108-4191, built 1948 (OpenAirDocs) - Reported make and model: Stinson 108-3 - Registry model: [Stinson 108-3](https://openairdocs.org/model/stinson-108-3) (registry code 9230408) (OpenAirDocs) - Registry engine: [Franklin 6A4165 series](https://openairdocs.org/engine/franklin-6a4165-series) (registry code 27025, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 108-4191 - Airframe hours: 2593 - Engines: Franklin 6A4-165-B3 165 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Registered owner: William J. Linn - Airworthiness certificate: Standard, Normal - Last inspection: Annual, June 20, 1998, 60 hours before - Departed: 7B6, EAST WINDSOR, CT - Destination: DXR, DANBURY, CT ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 53; student; airplane ratings: single-engine land; medical: class 3, valid medical--w/ waivers/lim; seat: left; flight hours: 1,076 total, 360 in this make and model ## Weather - Conditions: Visual (VMC), Day - Wind: 360° at 9 knots - Visibility: 10 statute miles - Lowest ceiling: 3,800 ft broken - Temperature: 34 °F, dew point 18 °F - Altimeter: 29.00 inHg - Observed at: HFD, 15 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 19990221001659A](https://openairdocs.org/incident/19990221001659A), Feb 21, 1999: Univar 1083, Bristol, CT, Destroyed. Pilot heard a loud noise and saw oil on the windshield. The pilot then declared an emergency and made an emergency landing in a field. Other circumstances are… 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.