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NTSB Final Report Released: Caldwell, ID


 

Location:

Caldwell, ID

Accident Number:

WPR18LA050

Date & Time:

12/17/20171300 MST

Registration:

N716JB

Aircraft:

GRAY JIM ROBERT EXEC

Aircraft Damage:

Substantial

Defining Event:

Powerplant sys/comp malf/fail

Injuries:

1 None

Flight Conducted Under:

Part 91: General Aviation - Personal


Analysis
The private pilot was performing hover-taxi maneuvers in the experimental amateur-built helicopter when the engine lost all power, which resulted in a forced landing in a field during which the airplane landed hard. Postaccident examination revealed that the engine had seized due to oil exhaustion after the oil pressure gauge line had failed, causing most of the engine oil to be expelled overboard with an insufficient quantity of oil in the sump for engine operation.

The pilot, who was also the helicopter builder, had installed the oil pressure gauge line, which was made of automotive-grade nylon tubing, about 1 year before the accident. Because the helicopter had an experimental airworthiness certificate and was considered to be an amateur-built aircraft, the pilot could use non-aviation grade components. The pilot discarded the oil line before it could be examined, so its failure mode could not be determined.

Probable Cause and Findings
The National Transportation Safety Board determines the probable cause(s) of this accident to be:

Failure of the oil pressure gauge line, which resulted in oil exhaustion and a total loss of engine power.


Findings

Aircraft

Engine oil indicating system - Failure (Cause)

Oil - Fluid level (Cause)

Factual Information

History of Flight

Maneuvering-hover

Powerplant sys/comp malf/fail (Defining event)

Loss of engine power (total)

Emergency descent

Off-field or emergency landing

Landing

Hard landing


On December 17, 2017, about 1300 mountain standard time, an experimental amateur-built Rotorway Exec-90 series helicopter, N716JB, landed hard following a loss of engine power at Caldwell Industrial Airport, Caldwell, Idaho. The private pilot/builder was not injured, and the helicopter sustained substantial damage to the lower fuselage structure. The helicopter was registered to and operated by the pilot under the provisions of Title 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed, and no flight plan had been filed. The local flight departed Caldwell about 1230.

The pilot stated that he planned to perform a series of hover-taxi and air-taxi maneuvers on taxiway A as practice, after a two-week period of bad weather. After taxiing around the airport for about 30 minutes, he heard an unusual sound and the engine began to lose power. He was initiating a turn at the time, and as the helicopter descended to 10 ft, the engine lost all power. He performed a forced landing, and the helicopter landed hard.

Examination of the helicopter revealed that oil was leaking from below the engine compartment, and a trail of oil was present on the ground in the areas that the helicopter had been taxing.

Following the accident, the pilot recovered the helicopter to his hangar and removed the body panels around the engine. He stated that the sump contained about 2 quarts of oil (capacity 5 quarts), and the engine appeared to have seized. An inspector from the Federal Aviation Administration (FAA) performed an external inspection and found that all the visible major oil lines were intact and tight at their fittings, and there did not appear to be any catastrophic breaches or damage to the engine crankcase.

A few months after the accident the pilot began to disassemble the helicopter for repair, and discovered that the oil pressure gauge line, which was attached to the oil filter housing by a brass compression fitting, had failed and separated from the fitting. He stated that the line was made of nylon tubing, which he purchased from a local automobile parts store.

He had installed the tubing about one year before the accident, after the original kit-supplied plastic line had degraded and was leaking oil into the cabin.

The pilot discarded the oil line before it could be examined by the FAA or NTSB.

According to FAA Advisory Circular AC 20-27G, Certification and Operation of Amateur-Built Aircraft, "Amateur builders are free to develop their own designs or build from existing designs. We do not approve these designs and it would be impractical to develop design standards for the wide variety of design configurations, created by designers, kit manufacturers, and amateur builders."

Previous Accidents
The pilot was involved in three previous accidents in the accident helicopter, all involving a loss of power:

On October 19, 2016, the helicopter lost power during the initial takeoff climb (accident number: WPR17LA009). The NTSB determined the probable cause to be, "The pilot's failure to properly tighten the tension bolts during the installation of the alternator belt, which resulted in inadequate voltage to sustain ignition and the subsequent partial loss of engine power."

On September 5, 2002, the helicopter lost power shortly after takeoff (accident number: FTW02LA250). The NTSB determined the probable cause to be, "The pilot's failure to refuel the helicopter, which resulted in fuel exhaustion."

On October 1, 1999, the helicopter lost power while in the traffic pattern (accident number: DEN00LA001). The NTSB determined the probable cause to be, "The pilot inadvertently allowing main rotor rpm to decay while avoiding obstacles during an emergency autorotation following a loss of power for reasons undetermined. Factors were houses and powerlines."



Administrative Information

Investigator In Charge (IIC):

Eliott Simpson

Adopted Date:

02/05/2019

Additional Participating Persons:

Edwin Lord; FAA FSDO; Boise, ID

Publish Date:

02/05/2019

Note:

The NTSB did not travel to the scene of this accident.

Investigation Docket:

http://dms.ntsb.gov/pubdms/search/dockList.cfm?mKey=96490

Pilot Information

Certificate:

Private

Age:

70, Male

Airplane Rating(s):

Single-engine Land

Seat Occupied:

Left

Other Aircraft Rating(s):

Helicopter

Restraint Used:

4-point

Instrument Rating(s):

Airplane; Helicopter

Second Pilot Present:

No

Instructor Rating(s):

None

Toxicology Performed:

No

Medical Certification:

Class 3 With Waivers/Limitations

Last FAA Medical Exam:

03/30/2016

Occupational Pilot:

No

Last Flight Review or Equivalent:

10/19/2017

Flight Time:

691 hours (Total, all aircraft), 317 hours (Total, this make and model), 33.4 hours (Last 90 days, all aircraft), 11.1 hours (Last 30 days, all aircraft), 0 hours (Last 24 hours, all aircraft)

 

 

 

 

Aircraft and Owner/Operator Information

Aircraft Make:

GRAY JIM ROBERT

Registration:

N716JB

Model/Series:

EXEC 90

Aircraft Category:

Helicopter

Year of Manufacture:

1998

Amateur Built:

Yes

Airworthiness Certificate:

Experimental

Serial Number:

EXEC-3000

Landing Gear Type:

Skid

Seats:

2

Date/Type of Last Inspection:

08/05/2017, Condition

Certified Max Gross Wt.:

1350 lbs

Time Since Last Inspection:

21 Hours

Engines:

1 Reciprocating

Airframe Total Time:

317 Hours at time of accident

Engine Manufacturer:

Rotorway

ELT:

Not installed

Engine Model/Series:

RW-152

Registered Owner:

On file

Rated Power:

152 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:

KEUL, 2429 ft msl

Distance from Accident Site:

0 Nautical Miles

Observation Time:

1956 UTC

Direction from Accident Site:

14°

Lowest Cloud Condition:

 

Visibility

10 Miles

Lowest Ceiling:

Overcast / 6000 ft agl

Visibility (RVR):

 

Wind Speed/Gusts:

3 knots /

Turbulence Type Forecast/Actual:

/

Wind Direction:

90°

Turbulence Severity Forecast/Actual:

/

Altimeter Setting:

30.28 inches Hg

Temperature/Dew Point:

2°C / -5°C

Precipitation and Obscuration:

No Obscuration; No Precipitation

Departure Point:

Caldwell, ID (EUL)

Type of Flight Plan Filed:

None

Destination:

Caldwell, ID (EUL)

Type of Clearance:

None

Departure Time:

1230 MST

Type of Airspace:

Class G

  

 

Airport Information

Airport:

CALDWELL INDUSTRIAL (EUL)

Runway Surface Type:

N/A

Airport Elevation:

2431 ft

Runway Surface Condition:

Dry

Runway Used:

N/A

IFR Approach:

None

Runway Length/Width:

 

VFR Approach/Landing:

None

 

 

 

Wreckage and Impact Information

Crew Injuries:

1 None

Aircraft Damage:

Substantial

Passenger Injuries:

N/A

Aircraft Fire:

None

Ground Injuries:

N/A

Aircraft Explosion:

None

Total Injuries:

1 None

Latitude, Longitude:

43.641944, -116.635833 (est)

 





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