# NTSB MIA98FA229: Bell 47G-4A, N7162M, Carrollton, AL, August 23, 1998 - Type: NTSB accident investigation - Classification: Accident · No injuries · Field investigation · Final report - Date: August 23, 1998, 16:00 local (21:00 UTC) - Place: Carrollton, AL - Coordinates: 33.259483, -88.089294 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=33.2595&lon=-88.0893&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report February 15, 2001 - Report: Approved by Office Director - NTSB case key (mKey): 43783 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=MIA98FA229 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/43783/pdf - Page: https://openairdocs.org/ntsb/MIA98FA229 ## Probable cause The pilots failure to follow written instructions in the flight manual for an engine failure, and the improper use of flight controls (cyclic/collective) during an autorotation resulting in a hard landing, and collision of the main rotor blades with the tailboom assembly. Contributing to the accident was the improper installation of circlips on the counterweight assembly during an engine overhaul. This resulted in a subsequent total failure of the number 5 connecting rod. ## Analysis The pilot stated he was in cruise flight at about 75 feet over trees after completing a swath run when the engine quit. He started a right turn before he entered autorotation, and did not monitor the engine or rotor rpm. He started a deceleration at about 30 feet and pulled all collective pitch. The helicopter collided with the ground hard, and the main rotor blades collided with the tailboom assembly. Examination of the engine assembly revealed 10 of 22 circlips were installed incorrectly during engine overhaul resulting in the subsequent failure of the number 5 connecting rod. ## Factual narrative HISTORY OF FLIGHT On August 23, 1998, about 1600 central daylight time, a Bell 47G-4A, N7162M, registered to Southern Helicopters, operating as a 14 CFR Part 137 aerial application flight, experienced a reported total loss of engine power. The helicopter landed hard during a forced landing in the vicinity of Carrolton, Alabama. Visual meteorological conditions prevailed and no flight plan was filed. The helicopter sustained substantial damage. The commercial pilot reported no injuries. The flight originated from a field site location about 5 minutes before the accident. The pilot stated he had just completed a swath run and was in cruise flight over trees at about 75 feet when the engine quit. He started a right turn before he entered autorotation. He did not monitor his engine or rotor rpm. He started a deceleration at about 30 feet with very little forward airspeed. The helicopter entered a vertical rate of descent. He pulled all collective pitch at about 10 feet. The helicopter collided with the ground hard and the main rotor blades collided with the tailboom assembly. PERSONNEL INFORMATION Information pertaining to First Pilot Information is found on page 3 of this report, and in NTSB Form 6120.1/2 Pilot Information. AIRCRAFT INFORMATION Review of the engine logbooks revealed the last recorded annual inspection and engine overhaul was conducted on January 20, 1998. The engine had accumulated 246.5 hours since overhaul/ annual inspection. The last recorded 100-hour inspection was conducted on June 9, 1998. The last recorded 50- hour inspection was conducted on July 1, 1998. According to the airframe and powerplant mechanic with inspection authority, the engine was overhauled by himself at his company in Guam named Tropic Helicopters Inc. The company was closed and the engine was shipped to his residence in Alabama, and installed on N7162M. METEOROLOGICAL INFORMATION Visual meteorological conditions prevailed at the time of the accident. (For additional information see Weather Information on page 4 of this report). WRECKAGE AND IMPACT INFORMATION According to the Pickens County Sheriff Department, Carrollton, Alabama, the wreckage of N7162M was located in a field about 2.9 miles east of highway 17 south and county road 22 in the vicinity of Carrollton, Alabama. No accident crashsite investigation was conducted by the Federal Aviation Administration (FAA) or the NTSB. The accident was reported to the NTSB on August 25, 1998, by the FAA Birmingham Flight Standards District Office, Birmingham, Alabama, as a reported engine failure which resulted in substantial damage. On August 26, 1998, the NTSB investigator-in-charge (IIC) was contacted by an insurance adjuster from Carson-Brooks, Inc., Atlanta, Georgia. The adjuster informed the IIC that there appeared to be a bullet hole in the engine crankcase next to the number 4 cylinder. Local law enforcement authorities were notified and the helicopter was transported to an authorized repair facility for analysis by the NTSB, FAA, and law enforcement personnel. Examination of the helicopter revealed scarring was present on the bottom of the helicopter tail guard assembly from contact with the ground. The helicopter continued forward and collided with the ground in a right skid low attitude. The forward and aft cross tube assemblies were bowed in the middle with evidence of right lateral shift on the saddle straps. The left skid was rotated to the right 90 degrees. The forward and aft legs failed forward and to the right. The right skid was rotated to the right about 30 degrees. The forward and aft legs failed forward and to the right. The aft leg separated from the skid assembly. The right underside fuselage was compressed upward with the floor assembly on the cabin assembly. Minor damage was present on the left underside fuselage of the cabin assembly. The bubble assembly was broken. The left and right fuel tanks were not damaged. The lower truss type fuselage failed at the jack point at FS80. The upper right truss attach point failed 10 inches outboard of the attach point, and was bowed in to the right at about FS90. The upper left truss attach point was intact. The truss type attach fuselage separated at FS160, FS179, and FS225. The vertical fin, tailrotor extension shaft, and tailrotor guard assembly separated from the truss type fuselage. Examination of the main rotor system and tailrotor system revealed no evidence of a precrash mechanical failure or malfunction. The yellow main rotor blade collided with the truss type fuselage, tailrotor extension shaft, and the drag brace separated from the main rotor blade. A hole was present on the bottom side of the main rotor blade 20 inches inboard of the blade tip. Chordwise scarring and transfer of blue and white paint was present on the bottom and top of the main rotor blade. No leading edge damage was present. The red main rotor blade collided with the truss type fuselage, and tailrotor extension shaft, and the drag brace separated from the main rotor blade. A hole was present in the bottom and top side of the main rotor blade about 25 inches from the tip. Chordwise scarring and transfer of blue and white paint was present on the bottom and top of the main rotor blade. No leading edge damage was present. The tailrotor blade, serial number 1855, separated 13 inches outboard of the hub assembly. The hub static stop contacted the yoke assembly. The tailrotor blade, serial number 1851, separated 10 inches outboard of the hub assembly. The hub static stop contacted the yoke assembly. Examination of the airframe and flight control assembly revealed no evidence of a precrash mechanical failure or malfunction. Continuity of the flight control system was confirmed for pitch, roll, and yaw. Examination of the main transmission, engine to transmission, and overrunning clutch revealed no evidence of a precrash mechanical failure or malfunction. The number one drive shaft assembly and number two drive shaft assembly separated and were not recovered. The number three drive shaft assembly separated. Examination of the engine assembly revealed a round hole about 1/2 inch in diameter in the vicinity of the 11 o'clock position on the right side of the helicopter below the number 4 cylinder base (left engine case half). Cracks were present in the crankcase in the near the base of the number 5 cylinder. Disassembly of the engine revealed the number 5 connecting rod assembly was detached. The connecting rod cap was broken in two pieces. Both connecting rod bolts were broken. There was no evidence of heat distress on the number r journal or bearing inserts. Galling was present on the inner diameter, inner bore of the connecting rod yoke, and on the connecting rod cap. Examination of the number 1 counterweight assembly revealed two of four circlips located in both aft positions were installed with the sharp edge inward. The number 2 counterweight assembly was found with three of four circlips installed with the sharp edge inward. One was located at the forward leading position, and two were located in the aft position. The number 3 counterweight assembly was found with one of four circlips installed with the sharp edge inward, located in the aft trailing position. The number 4 counterweight assembly was found with one of four circlips installed with the sharp edge inward in the aft trailing position. The number 5 counterweight assembly was found with one of four circlips installed with the sharp edge inward in the aft leading position. The number 6 counterweight assembly was found with two of four circlips installed with the sharp edge inward in both aft positions. The circlip located at the aft trailing position was broken in half. One half of the circlip remained in place, and it was installed with the sharp edge inward. The remains of the remaining half was located in the engine accessory compartment. T ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power, cruise - eng assembly,crankshaft counterweights/vib damper - assembly - instructions,written/verbal - not followed, other maintenance personnel (contributing factor) - engine assembly,connecting rod - failure,total - Forced landing, maneuvering - turn to landing area (emergency) - Hard landing, landing - flare/touchdown - terrain condition - ground - autorotation - performed, pilot in command - emergency procedure - not followed, pilot in command (cause) - flight controls - improper use of, pilot in command (cause) ## Aircraft - Registration: [N7162M](https://openairdocs.org/aircraft/N7162M), registered now, S/N 7569, built 1967 (OpenAirDocs) - Reported make and model: Bell 47G-4A - Registry model: [Bell 47G-4A](https://openairdocs.org/model/bell-47g-4a) (registry code 1181031) (OpenAirDocs) - Registry engine: [Lycoming VO-540 series](https://openairdocs.org/engine/lycoming-vo-540-series) (registry code 41534, reciprocating) (OpenAirDocs) - Category: Helicopter - Serial number: 7569 - Airframe hours: 7065 - Engines: Lycoming VO-540-B1B3 reciprocating - Damage: Substantial damage - Flight: Aerial application, Part 137 - Operator: Nelson E. Tucker - Registered owner: Southern Helicopters - Airworthiness certificate: Special, Restricted (Special) - Last inspection: Continuous airworthiness, June 9, 1998, 89 hours before - Departed: NONE ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 55; commercial; airplane ratings: single-engine land; medical: class 2, valid medical--w/ waivers/lim; seat: left; flight hours: 15,000 total, 1,200 in this make and model, 75 in the last 90 days ## Weather - Conditions: Visual (VMC), Day - Wind: 40° at 4 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 90 °F, dew point 66 °F - Altimeter: 29.00 inHg - Observed at: TCL, 28 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 19980823021849A](https://openairdocs.org/incident/19980823021849A), Aug 23, 1998: Bell 47G4A, Carrollton, AL, Substantial damage. 1967 Bell 47G-4A helicopter experienced an interruption of engine power at a low altitude, and the acft made an emergency hard landing. (.4) history of flight… 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.