Saturday, April 6, 2019

Navion Navion G Rangemaster, registered to Kalea Company LLC and operated by SkyWalker Flying, N249KC: Accident occurred August 11, 2017 near Lenawee County Airport (KADG), Adrian, Michigan

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

Additional Participating Entities:

Federal Aviation Administration / Flight Standards District Office; Belleville, Michigan
Continental Motors; Mobile, Alabama 

Aviation Accident Final Report - National Transportation Safety Board:

Investigation Docket - National Transportation Safety Board:     

Aviation Accident Data Summary - National Transportation Safety Board:   

Location: Adrian, MI
Accident Number: CEN17LA316
Date & Time: 08/11/2017, 1200 EDT
Registration: N249KC
Aircraft Damage: Substantial
Defining Event: Loss of engine power (partial)
Injuries: 2 Serious
Flight Conducted Under: Part 91: General Aviation - Instructional 


The flight instructor and private pilot had completed training maneuvers and were returning to the airport when the engine experienced a partial loss of power about 1,000 to 1,500 ft above ground level. They were unable to glide the airplane to an open field and descended into a wooded area. The airplane impacted trees and became wedged between trees, suspended above the ground. The engine and empennage separated from the rest of the airplane and came to rest on the ground nearby. The fuel tanks were damaged and most of the remaining fuel spilled onto the ground.

A postaccident examination of the engine revealed no pre-impact anomalies that would have precluded normal operation or production of rated horsepower; however, an examination of the gascolator showed that it had been leaking fuel from three locations and contained a significant amount of debris. In a postaccident examination, the gascolator was subjected to the relevant service bulletin testing and did not pass the test due to the leaking seals and drain valve. Since the gascolator was unable to seal properly, it would have allowed air into the fuel system, which would have resulted in a loss of engine power. A review of the airplane maintenance records revealed no record of compliance with the service bulletin, nor was compliance mandatory.

Probable Cause and Findings

The National Transportation Safety Board determines the probable cause(s) of this accident to be:
A leak in the gascolator, which allowed air to enter the fuel system and resulted in a partial loss of engine power.


Fuel distribution - Damaged/degraded (Cause)
Fuel distribution - Not serviced/maintained (Cause)

Personnel issues
Scheduled/routine inspection - Maintenance personnel
Scheduled/routine maintenance - Maintenance personnel

Factual Information

On August 11, 2017, about 1200 eastern daylight time, a Navion G airplane, N249KC, impacted trees after a loss of engine power near Adrian, Michigan. The flight instructor and private pilot were seriously injured and the airplane sustained substantial damage. The airplane was registered to Kalea Co. LLC and operated by Sky Walker Flying under the provisions of Title 14 Code of Federal Regulations Part 91 as an instructional flight. Visual meteorological conditions prevailed at the time of the accident and a flight plan had not been filed. The local flight departed Lenawee County Airport (ADG), Adrian, Michigan, about 1000.

According to the flight instructor, the engine experienced a loss of power about 1,000 ft above ground level (agl) while over a wooded area and she was unable to glide the airplane to a nearby field. She stated to the sheriff's office that after the accident she walked to a nearby road and waited for a car to pass by for help.

The private pilot stated to the sheriff's office that he was flying the airplane and they were returning to the airport after completing training maneuvers. He stated that the engine experienced a partial loss of power about 1,500 ft agl. He added that the engine still had a little power available during the event.

The responding Federal Aviation Administration (FAA) inspector reported that the airplane was found wedged between trees with the empennage separated from the rear fuselage and engine separated from the firewall (figure 1). There was a smell of aviation fuel at the accident site.

Figure 1 – The airplane suspended above the ground and wedged between trees

A postaccident examination of the airplane was conducted by the FAA inspector and a technical representative from Continental Motors. The examination revealed that more than 4 gallons of fuel was drained from left wing tip tank, which remained intact. The right wing tip tank was found breached and had separated from the wing; there was no fuel present in the tank. The fuel gascolator, which is the low point of the center main fuel tanks, did not contain any fuel. There were fuel stain marks underneath the gascolator as it was installed on the airplane. The gascolator was removed for further testing.

An examination of the engine revealed the engine sustained impact damage concentrated mostly to the left rear side and the crankcase remained intact. All six cylinders remained attached to the engine and displayed impact damage signatures with the left side cylinders sustaining more damage than the right. The induction and exhaust systems both displayed impact damage signatures, but there were no signs of exhaust or induction leaks noted. The fuel pump was impact damaged as were several of the fuel line fittings. The throttle and metering assembly remained attached to the engine and displayed impact damage signatures; both the throttle and mixture arms were broken. The fuel manifold valve remained attached to its installation point and displayed impact damage signatures at the rear fitting. All of the fuel nozzles remained installed in their cylinders and there were no signs of fuel leaks near the nozzles. The 2 magnetos were undamaged and produced a spark at each ignition lead when manually rotated. The ignition harness displayed impact damage signatures to several of the left side cylinder ignition leads. All of the spark plugs remained installed in their cylinders and the top left spark plugs displayed impact damage signatures. The three-blade, constant speed propeller remained attached to the crankshaft and one of the blades was impact damaged. There were no pre-impact anomalies with the engine that would have precluded normal operation or production of rated horsepower.

The gascolator top and bottom seals were comprised of rubber gaskets which were meshed to a wire screen by a glass cylinder. As assembled the glass cylinder was tightened between two caps which each contained the rubber gaskets and wire mesh. The gascolator was examined by an FAA inspector who reported that there were fuel stains on the top seal and the drain valve, indicative of a fuel leak at some point during the life of the unit (figure 2).

Figure 2 – Gascolator installed on the airplane 

Sierra Hotel Aero, Inc. (SHA) holds the type certificate for the Navion. In May of 2007, SHA issued Navion Service Bulletin (SB) 106A - Fuel System - Inspection of the fuel system continued safe operation. The purpose of the SB was to require accomplishment of one time inspection of entire fuel system. This included from firewall aft for condition of all fuel lines installed including tip tanks, metal lines, fittings, hoses, vent system, vapor return, boost pump, and fuel strainer. The SB further states, inspect fuel strainer for evidence of fuel staining and leaking. Disassemble strainer and clean fuel screen. Inspect for damage and reassemble. Perform vacuum test of gascolator to include: connect hand operated vacuum pump and apply 24" of vacuum, verify bleed down does not exceed 4" over one minute, replace gaskets, fuel drain and/or gascolator as needed to ensure proper operation.

The gascolator was subjected to postaccident testing as prescribed in the Navion SB No. 106 A. The outlet port was plugged using an appropriate AN plug fitting. The gascolator was filled with clean 100LL fuel. After the fuel was added, a significant amount of foreign debris was observed floating in the gascolator. A 7-inch aluminum line with AN fittings was attached to the inlet port and the other end to the gascolator. This line was previously leak checked with no anomalies found. The inspector applied 24 inches of vacuum pressure using a hand vacuum pump; the gascolator was tested and failed to hold the required 24 inches of vacuum pressure for any amount of time. During the test the gascolator was leaking from the top seal, bottom seal, and the drain valve.

A review of the airplane maintenance logbooks revealed no record of compliance with the Navion SB No. 106 A, and there was no mention of gascolator maintenance from December 2006 to July 2017. 

Flight Instructor Information

Certificate: Flight Instructor; Commercial
Age: 52, Female
Airplane Rating(s): Multi-engine Land; Single-engine Land
Seat Occupied: Right
Other Aircraft Rating(s):
Restraint Used: Lap Only
Instrument Rating(s): Airplane
Second Pilot Present: Yes
Instructor Rating(s): Airplane Single-engine; Instrument Airplane
Toxicology Performed: No
Medical Certification: Class 2 With Waivers/Limitations
Last FAA Medical Exam: 12/01/2016
Occupational Pilot: Yes
Last Flight Review or Equivalent: 06/23/2016
Flight Time:  1700 hours (Total, all aircraft), 32 hours (Total, this make and model), 1500 hours (Pilot In Command, all aircraft), 80 hours (Last 90 days, all aircraft), 30 hours (Last 30 days, all aircraft)

Pilot Information

Certificate: Private
Age: 49, Male
Airplane Rating(s): Single-engine Land
Seat Occupied: Left
Other Aircraft Rating(s): None
Restraint Used: Lap Only
Instrument Rating(s): Airplane
Second Pilot Present: Yes
Instructor Rating(s): None
Toxicology Performed: No
Medical Certification: Class 2 With Waivers/Limitations
Last FAA Medical Exam: 01/23/2017
Occupational Pilot: No
Last Flight Review or Equivalent: 12/13/2015
Flight Time: (Estimated) 

Aircraft and Owner/Operator Information

Aircraft Make: NAVION
Registration: N249KC
Model/Series: NAVION G
Aircraft Category: Airplane
Year of Manufacture: 1964
Amateur Built: No
Airworthiness Certificate: Normal
Serial Number: NAV-4-2499
Landing Gear Type: Retractable - Tricycle
Seats: 4
Date/Type of Last Inspection: 07/05/2017, Annual
Certified Max Gross Wt.: 
Time Since Last Inspection: 5 Hours
Engines: 1 Reciprocating
Airframe Total Time: 2089.06 Hours at time of accident
Engine Manufacturer: Continental Motors
ELT: Installed, not activated
Engine Model/Series: IO-520BA
Registered Owner: KALEA CO LLC
Rated Power: 285 hp
Operator: Skywalker Flight School, LLC.
Operating Certificate(s) Held: None
Operator Does Business As: SkyWalker Flying
Operator Designator Code: 

Meteorological Information and Flight Plan

Conditions at Accident Site: Visual Conditions
Condition of Light: Day
Observation Facility, Elevation: KADG, 796 ft msl
Distance from Accident Site: 2 Nautical Miles
Observation Time: 1153 EDT
Direction from Accident Site: 355°
Lowest Cloud Condition: Clear
Visibility: 10 Miles
Lowest Ceiling: None
Visibility (RVR):
Wind Speed/Gusts: 7 knots /
Turbulence Type Forecast/Actual: /
Wind Direction: 220°
Turbulence Severity Forecast/Actual: /
Altimeter Setting: 29.99 inches Hg
Temperature/Dew Point: 22°C / 18°C
Precipitation and Obscuration: No Obscuration; No Precipitation
Departure Point: ADRIAN, MI (ADG)
Type of Flight Plan Filed: None
Destination: ADRIAN, MI (ADG)
Type of Clearance: None
Departure Time: 1000 EDT
Type of Airspace: Class E

Airport Information

Runway Surface Type: 
Airport Elevation: 798 ft
Runway Surface Condition: Unknown
Runway Used: N/A
IFR Approach: None
Runway Length/Width:
VFR Approach/Landing: Forced Landing 

Wreckage and Impact Information

Crew Injuries: 2 Serious
Aircraft Damage: Substantial
Passenger Injuries: N/A
Aircraft Fire: None
Ground Injuries: N/A
Aircraft Explosion: None
Total Injuries: 2 Serious
Latitude, Longitude: 41.829167, -84.074444 (est)

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