# NTSB BFO94LA010: Gulfstream American AA-5B, N28215, Sterling, MA, November 14, 1993 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Limited investigation · Final report - Date: November 14, 1993, 10:30 local (15:30 UTC) - Place: Sterling, MA - Location: 42.4376° N, 71.7606° W: Placed by OpenAirDocs: center of Sterling, MA, within about 6 miles (OpenAirDocs) - Nearby events: https://openairdocs.org/map.md?lat=42.4376&lon=-71.7606&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: Minor injuries - Injuries: 4 minor - Status: Completed, report October 20, 1994 - Report: Approved by Office Director - NTSB case key (mKey): 8868 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=BFO94LA010 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/8868/pdf - Page: https://openairdocs.org/ntsb/BFO94LA010 ## Probable cause SEPARATION OF THE NUMBER ONE EXHAUST VALVE DUE TO FATIGUE CRACKING WHICH RESULTED IN LOSS OF ENGINE POWER. OTHER RELATED FACTORS WERE MISJUDGMENT OF ALTITUDE AND AIRSPEED BY THE PILOT RESULTING IN ON GROUND COLLISION WITH THE TERRAIN AND SUBSEQUENT NOSE OVER. ## 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 - engine assembly,valve,exhaust - fatigue (cause) - Forced landing, descent - emergency - On ground/water encounter with terrain/water, landing - roll - altitude - misjudged, pilot in command (contributing factor) - airspeed - misjudged, pilot in command (contributing factor) - Nose over, landing - roll ## Analysis THE PILOT REPORTED THAT THE AIRPLANE WAS AT 2000 FEET MSL WHEN A SEVERE VIBRATION DEVELOPED ON THE AIRPLANE. HE STATED THAT THE AIRPLANE WAS DESCENDING AT 200 FEET PER MINUTE WITH THE THROTTLE FULL FORWARD, AND 1700 RPM ON HIS GAGE. HE STATED THAT THE NEAREST AIRPORT WAS ABOUT 6 MILES AWAY, SO HE RADIOED THE AIRPORT OF HIS SITUATION AND ENTERED THE TRAFFIC PATTERN ON THE BASE LEG. HE STATED THAT HE WAS HIGH ON THE APPROACH, BUT HE RECALLED FROM HIS TRAINING THAT IT WAS BETTER TO BE HIGH AND FAST THAN LOW AND SLOW. THE AIRPLANE TOUCHED DOWN ABOUT HALF WAY DOWN THE 3100 FOOT LONG RUNWAY AND EXITED INTO A SIX FOOT CULVERT WHERE IT NOSED OVER. AN EXAMINATION OF THE ENGINE BY THE FAA REVEALED A LEAK WHEN A COMPRESSION TEST WAS COMPLETED. THE CYLINDER WAS REMOVED AND SENT TO THE NTSB LAB IN WASHINGTON, DC. A METALLURGICAL EXAMINATION REVEALED THE EXHAUST VALVE SEPARATED AS A RESULT OF FATIGUE CRACKING THAT INITIATED IN THE RADIUS BETWEEN THE STEM AND THE HEAD OF THE VALVE. ## Factual narrative On Sunday, November 14, 1993, about 1030 eastern standard time, N28215, a Gulfstream American Corp. AA-5B, owned and operated by James Connelly of Maynard, Massachusetts, collided with the ground and nosed over on landing following a power-off forced landing at Sterling Airport, Sterling, Massachusetts. Visual meteorological conditions prevailed and a flight plan was not filed. The certificated private pilot, and his three passengers received minor injuries. The airplane was substantially damaged. The personal flight originated in Fitchburg, Massachusetts, and was conducted under 14 CFR 91. According to the pilot, the airplane was at an altitude of 2000 feet MSL when he experienced a "severe vibration." He stated that the nearest airport was about 6 miles away, so he radioed the airport and reported that he was going to make a landing at that airport. He stated that he entered the traffic pattern on the base leg, and that the airplane was high on the approach. The pilot stated that during his training he was taught that "it is better to be high and fast than low and slow." The airplane touched down about half way down the 3100 foot long runway then exited into a six foot culvert and nosed over. The engine was removed to a hangar at Sterling Airport for further examination under the supervision of the FAA. The examination involved removing the lower spark plugs, and conducting a compression test. The examination revealed a leakage from both number one and two cylinders. The two cylinders were removed and sent to the NTSB Lab in Washington, DC for further examination. The examination involved the removal of the intake and exhaust valves from the number one cylinder assembly. The number two cylinder assembly and piston were submitted for comparison purposes. Examination of the number one exhaust valve revealed a fracture. Visual examination of the fracture with the aid of a bench binocular microscope revealed the presence of a crack that initiated in the radius between the stem and the head of the valve. ## Aircraft - Registration: [N28215](https://openairdocs.org/deregistered/N28215-1994-02-17), registration cancelled 1994-02-17, S/N AA5B0941 (OpenAirDocs) - Reported make and model: GULFSTREAM AMERICAN AA-5B - Registry model: [Gulfstream American AA-5B](https://openairdocs.org/model/gulfstream-american-aa-5b) (registry code 3970106) (OpenAirDocs) - Category: Airplane - Serial number: AA5B-0941 - Airframe hours: 1300 - Engines: LYCOMING O-360-A4K 180 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Operator: James Connelly - Registered owner: James Connely - Airworthiness certificate: Standard, Normal - Last inspection: Annual, October 4, 1993, 13 hours before - Departed: 6B6, STOW, MA - Airport: 3B3, Sterling, runway 16, 3,010 × 40 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 44; private; airplane ratings: single-engine land; medical: class 3, valid medical--no waivers/lim.; seat: left; flight hours: 348 total, 348 in this make and model, 302 as pilot in command, 19 in the last 90 days, 8 in the last 30 days, 2 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 270° at 11 knots, gusting 19 - Visibility: 20 statute miles - Lowest ceiling: 25,000 ft broken - Temperature: 61 °F, dew point 52 °F - Altimeter: 30.00 inHg - Observed at: ORH, 10 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 19931114042649A](https://openairdocs.org/incident/19931114042649A), Nov 14, 1993: Gulstm AA5B, Sterling, MA, Substantial damage. Severe vibration. Made high fast approach to nearby 3B3. Landed long ran off into a culvert. Exhaust valve cracked. 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.