Monday, November 11, 2019

Loss of Engine Power (Total): Grumman AA-1B Trainer, N6550L; accident occurred May 15, 2018 at Butler County Regional Airport (KHAO), Hamilton, Ohio

The National Transportation Safety Board did not travel to the scene of this accident.

Additional Participating Entities:

Federal Aviation Administration / Flight Standards District Office; Cincinnati, Ohio
Lycoming Engines; Williamsport, Pennsylvania 
Aviation Accident Factual Report - National Transportation Safety Board:

Investigation Docket - National Transportation Safety Board: 

Location: Hamilton, OH
Accident Number: CEN18LA173
Date & Time: 05/15/2018, 0945 EDT
Registration: N6550L
Aircraft Damage: Substantial
Defining Event: Loss of engine power (total)
Injuries: 1 Serious
Flight Conducted Under: Part 91: General Aviation - Flight Test 

On May 15, 2018, about 0945 eastern daylight time, a Grumman American Aviation Corporation AA 1B airplane, N6550L, impacted terrain during a forced landing at the Butler County Regional Airport-Hogan Field (HAO), near Hamilton, Ohio, following a loss of engine power. The commercial pilot, who was the sole occupant, sustained serious injuries. The airplane received substantial wing and fuselage damage. The airplane was registered to an individual and was operated by the pilot as a Title 14 Code of Federal Regulations Part 91 test flight. Day visual meteorological conditions prevailed in the area about the time of the accident, and the flight was not operated on a flight plan. The local flight was originating from HAO at the time of the accident.

According to the current owner of the accident airplane, the airplane was at HAO for a pre-purchase inspection and for an overhauled engine swap.

According to the prior owner of the accident airplane, he flew the accident airplane on April 12, 2018, about 1000. A maintenance test flight was going to be conducted because of an engine swap. After completing a preflight, 2 blocks of wood were found behind the rudder pedals that prevented them from moving. After removing them, the airplane failed a run up because of engine roughness.

The prior owner thought the flying was concluded as there was something wrong with the engine. The mechanic felt that the roughness was caused by oil getting by the new piston rings and fouling the sparkplugs. The mechanic removed the cowling and the fouled plugs. After cleaning them and reinstalling the plugs, the engine appeared to run "ok." Since the mechanic had an expired flight review, the prior owner ended up taking the right seat with him in the left seat for the maintenance test flight. He mentioned that he would have to run the engine at high power while taxiing to prevent fouling again. On taxi out, the mechanic was the pilot flying and the prior owner was the pilot monitoring. The prior owner was surprised when the mechanic took the active runway without doing an engine runup.

The takeoff power appeared normal until about 100 ft above ground level (AGL) where the engine abruptly lost power without warning. The airplane nosed over immediately, and they put the airplane down on the remaining runway, stopping about 30 ft from the end of the runway. The prior owner was upset that the engine lost power after the mechanic was so certain that it was the fouling of the plugs, and that the mechanic did not conduct a proper engine run up, especially in light of the engine roughness encountered on the previous taxi out.

The current owner reported that the mechanic then removed the carburetor and subsequently sent it out for overhaul and reinstallation.

The mechanic reinstalled the overhauled carburetor and conducted maintenance test flight. A witness at HAO heard the sound of the airplane's engine stop while the mechanic was conducting this takeoff. The witness then saw the airplane return to the airport for a landing. The airplane impacted terrain left wing low during the forced landing where it sustained the substantial damage. A video from a local parking lot camera shows the accident sequence and is appended to the docket material associated with this investigation.

The accident pilot held a commercial pilot certificate and an airframe and powerplant mechanic certificate. The pilot completed an accident report that did not contain a narrative of the accident flight and he advised that he did not recall the accident. However, the pilot reported that he had accumulated more than 6,000 hours of total flight time, more than 50 hours of flight time in AA 1B airplanes, and more than 300 hours of flight time in 2-seat Grumman airplanes. Additionally, he forwarded a statement from another airframe and powerplant mechanic, which is appended to the docket material associated with this investigation.

N6550L was a 1974-model Grumman American Aviation Corporation AA 1B airplane, with serial number AA1B-0350. It was a low-wing airplane, with a fixed tricycle landing gear, and was configured for two occupants. The airplane was powered by a direct drive, carbureted, air-cooled, four-cylinder engine. The engine was a Lycoming O-320-C2C, with serial number L-11445-15, which drove a two-bladed, fixed pitch, McCauley 1A105 SCM 7154 propeller. The airplane's logbooks showed that this engine was installed on the airplane and an annual inspection completed on April 3, 2018, at a tachometer time of 1,427.3 hours, total airframe time of 4,126 hours, total engine time of 6,758.4 hours, and 1.4 hours since the engine's last major overhaul. The airplane had a fuel capacity of 24 gallons. The forwarded statement from a mechanic, in part, advised that logbook documents showed that the engine was installed on N9971L from June 9, 2001, until March 5, 2007, when it was removed from N9971L and overhauled. This engine then sat on a shelf until it was installed on an airplane, N1447R, that was sold at auction.

The airplane was equipped with an J.P. Instruments Engine Data Management (EDM) 350 system which is a 3.5-inch square engine-monitoring instrument. Per J.P. Instruments, the EDM 350 unit works in the background, can monitor engine parameters three times a second, and will warn you instantly if any parameter exceeds the programmed limit.

The EDM 350 unit was removed and shipped to the National Transportation Safety Board Vehicle Recorder Laboratory. A Senior Recorder Laboratory Specialist examined the unit and noted that it had a damaged screen. However, it was otherwise in good condition and the data was extracted normally from the 350 unit. The download of the unit produced a manufacturer proprietary file. The proprietary file contained recordings for six flights, however, the data was marked as "BADFLT" and no engine data was recorded within each file. The unit stored the amount of fuel available and the amount of fuel used. The amount of fuel used displayed as 1.5 gallons. The amount of fuel available displayed 14.5 gallons.

On May 15, 2018, at 0953, the recorded weather at HAO was: Wind variable at 5 kts; visibility 10 statute miles; sky condition clear; temperature 26° C; dew point 17° C; altimeter 29.93 inches of mercury.

On April 12, 2018, at 0953, the recorded weather at HAO was: Wind 250° at 13 kts, gusting to 22 kts; visibility 10 statute miles; sky condition clear; temperature 28° C; dew point 17° C; altimeter 30.05 inches of mercury.

The temperature and dew point data for these days were plotted on a carburetor icing chart. The weather present on the accident day was conducive to moderate carburetor icing at cruise power and serious icing at descent power. The weather present on April 12, 2018, was conducive to serious carburetor icing at descent power. The plotted charts are appended to the docket material associated with this investigation.

On May 16 and 17, 2018, a Federal Aviation Administration (FAA) aviation safety inspector and an air safety investigator from Lycoming Engines examined the wreckage. The engine produced a thumb compression at all cylinders when the crankshaft was rotated and the engine was not subsequently disassembled. All bottom sparkplugs were coated with oil which is consistent with gravity settling oil on them. During the wreckage examination, a B-nut fitting on the left fuel tank exhibited discoloration consistent with fuel staining. There were no other preimpact anomalies found that would have kept the accident engine from operating normally.

The prior owner reported a similar engine power loss accident that occured about 35 years ago, in a Cessna 150, when he had an engine failure with a student pilot at approximately 400 ft AGL while taking off at night. It was an abrupt engine failure (without warning) after 30 minutes of doing night touch and go landings. The airplane was force landed straight ahead off the airport. The cause turned out to be a small piece of ice in the fuel selector on the floor that became loose after heating up or vibration, and subsequently lodged in the fuel line shutting off the fuel. The investigators were able to determine this after pulling out the fuel selector and allowing it to warm up in a can in a car.

The prior owner stated, "Both cases, the only option was a straight ahead landing. I was able to attempt a restart twice in the Cessna, but because of the lower altitude of the Grumman, we did not have time to attempt a restart. In that case it was more critical to get it on the remaining runway. I have no idea as to the cause of the failure in the Grumman, other that everything appeared normal in the initial Takeoff roll and Climb Out (before it failed completely and with very little warning (seconds at most)."

The emergency procedures section in the FAA Airplane Flying Handbook, in part, stated:

The altitude available is, in many ways, the controlling factor in the successful accomplishment of an emergency landing. If an actual engine failure should occur immediately after takeoff and before a safe maneuvering altitude is attained, it is usually inadvisable to attempt to turn back to the field from where the takeoff was made. Instead, it is safer to immediately establish the proper glide attitude, and select a field directly ahead or slightly too either side of the takeoff path. ...

To get back to the takeoff field, a downwind turn must be made. This increases the groundspeed and rushes the pilot even more in the performance of procedures and in planning the landing approach. Secondly, the airplane is losing considerable altitude during the turn and might still be in a bank when the ground is contacted, resulting in the airplane cartwheeling (which would be a catastrophe for the occupants, as well as the airplane). After turning downwind, the apparent increase in groundspeed could mislead the pilot into attempting to prematurely slow down the airplane and cause it to stall.

A review of a map of the area around HAO revealed that there was a business and housing present within a quarter mile from the end of the departure runway.

Pilot Information

Certificate: Commercial; Private
Age: 63, Male
Airplane Rating(s): Multi-engine Land; Single-engine Land
Seat Occupied: Left
Other Aircraft Rating(s): None
Restraint Used:
Instrument Rating(s): Airplane
Second Pilot Present: No
Instructor Rating(s): None
Toxicology Performed: No
Medical Certification: Class 3 With Waivers/Limitations
Last FAA Medical Exam: 01/02/2018
Occupational Pilot: No
Last Flight Review or Equivalent:
Flight Time: 6000 hours (Total, all aircraft), 50 hours (Total, this make and model)

Aircraft and Owner/Operator Information

Registration: N6550L
Model/Series: AA 1B
Aircraft Category: Airplane
Year of Manufacture: 1974
Amateur Built: No
Airworthiness Certificate: Normal
Serial Number: AA1B-0350
Landing Gear Type: Tricycle
Seats: 2
Date/Type of Last Inspection: 04/03/2018, Annual
Certified Max Gross Wt.: 1560 lbs
Time Since Last Inspection:
Engines: 1 Reciprocating
Airframe Total Time: 4126 Hours as of last inspection
Engine Manufacturer: Lycoming
ELT: Installed
Engine Model/Series: O-235-C2C
Registered Owner: Individual
Rated Power: 108 hp
Operator: On file
Operating Certificate(s) Held: None

Meteorological Information and Flight Plan

Conditions at Accident Site: Visual Conditions
Condition of Light: Day
Observation Facility, Elevation: KHAO, 634 ft msl
Distance from Accident Site: 0 Nautical Miles
Observation Time: 0953 EDT
Direction from Accident Site: 273°
Lowest Cloud Condition: Clear
Visibility:  10 Miles
Lowest Ceiling: None
Visibility (RVR):
Wind Speed/Gusts: 5 knots /
Turbulence Type Forecast/Actual:
Wind Direction: Variable
Turbulence Severity Forecast/Actual:
Altimeter Setting: 29.93 inches Hg
Temperature/Dew Point: 26°C / 17°C
Precipitation and Obscuration: No Obscuration; No Precipitation
Departure Point: Hamilton, OH (HAO)
Type of Flight Plan Filed: None
Destination: Hamilton, OH (HAO)
Type of Clearance: None
Departure Time: 0945 EDT
Type of Airspace:

Airport Information

Runway Surface Type: Asphalt
Airport Elevation: 633 ft
Runway Surface Condition: Dry
Runway Used: N/A
IFR Approach: None
Runway Length/Width:
VFR Approach/Landing: Forced Landing

Wreckage and Impact Information

Crew Injuries: 1 Serious
Aircraft Damage: Substantial
Passenger Injuries: N/A
Aircraft Fire: None
Ground Injuries: N/A
Aircraft Explosion: None
Total Injuries: 1 Serious
Latitude, Longitude: 39.363889, -84.521944 (est)

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