Aviation Accident Summaries

Aviation Accident Summary WPR17LA072

Carson City, NV, USA

Aircraft #1

N39894

BELLANCA 17-30A

Analysis

The airline transport pilot was conducting the airplane's first flight after about 1 1/2 years of inactivity and the completion of an annual inspection. A witness reported that the airplane took off normally, but the retractable landing gear remained extended. As the airplane neared the end of the runway, about 300 ft above ground level, the engine sounded as though it "decreased to idle." The airplane entered a right, 180o turn and descended rapidly before impacting the ground. During a postaccident test run, the engine operated normally at both idle and full power settings and during abrupt changes between idle and full power. However, it operated inconsistently at 2,100 rpm for about 30 seconds before stabilizing at that power setting. During this time, the fuel pump pressure fluctuated. Following the test run, the fuel manifold valve was disassembled, revealing rust on the screen, lower housing, and plunger, consistent with exposure to water. The diaphragm was removed and a small amount of fuel was found on the "dry" side of the valve; the vent extending from this section was examined and clear of debris. Examination of the airframe and engine maintenance logs revealed that the airplane flew a total of 73 hours and underwent 3 annual inspections in the previous 8 years. It is likely that water accumulated in the fuel system sometime during the airplane's prolonged periods of disuse, resulting in corrosion of the fuel manifold valve's internal components. Because the corrosion was internal, it would not have been detected without disassembly of the fuel manifold, which is not part of the annual inspection procedure. It is likely that this corrosion caused the manifold valve plunger to temporarily stick, which restricted fuel flow to the engine and resulted in the anomalous operation during the postaccident test run as well as the loss of power on the accident flight. Following the loss of engine power, the pilot initiated a turn back to the runway, during which the airplane exceeded its critical angle of attack and experienced an aerodynamic stall.

Factual Information

On March 1, 2017, about 1250 Pacific standard time, a Bellanca 17-30A, N39894, experienced a loss of engine power shortly after takeoff from the Carson Airport (CXP), Carson City, Nevada. The pilot, sole occupant, was seriously injured, and the airplane sustained substantial damage to both wings. The airplane was registered to and operated by the pilot as a 14 Code of Federal Regulations Part 91 personal flight. Visual meteorological conditions prevailed at the time of the accident no flight plan was filed for the local flight. At the time of this report, the pilot was unable to provide a statement or complete the NTSB Pilot/Operator Aircraft Accident/Incident Report Form 6120.1. A witness reported that he observed the airplane takeoff normally, with the exception that the landing gear remained in the down position. At the end of the runway, when the airplane was no higher than 300 feet, it sounded as if the engine decreased to idle. The airplane made a right 180o turn and descended rapidly before impacting the ground. Postaccident examination of the airframe revealed continuous control continuity throughout the airframe. In addition, control continuity was established from the cabin to the throttle, mixture, and propeller controls. The fuel lines were intact from the engine to the firewall, and from the wing tanks to the fuselage; the remaining lines were inaccessible due to airframe damage. Air was blown from the engine driven fuel pump inlet line aft through the fuel selector and air/fuel exited the left wing fuel tank outlet line. With no obvious anomalies with the airframe or engine, the engine was shipped to Continental Motors to be run in a test cell. The engine was installed into a test cell. It started normally and ran for a while at 1,200 RPM with no anomalies noted. The power was increased to 2,100 rpm and the engine operated inconsistently; the fuel pump pressure was fluctuating, and after about 30 seconds the engine stabilized. After stabilization, a magneto check was completed and no abnormalities were noted. The engine power was increased to 2,400 RPM momentarily before full power was applied; the engine continued to operate normally. The engine power was abruptly changed between idle and full power several times with no anomalies noted. Unable to recreate the inconsistent running engine, it was shut down normally and removed from the test cell. The fuel components were removed from the engine. The fuel manifold valve was disassembled and rust indicative of corrosion was present on the screen and lower housing of the unit. The plunger was removed and it also exhibited rust. The diaphragm was removed and a small amount of fuel was found on the "dry" side of the valve; the vent extending from this section was examined and clear of debris. The most recent entries from the airplane's airframe and engine maintenance logbooks were three annual inspections that occurred over a span of about 8 years. The tach time difference between these inspections was a total of 73 hours, for an average of 9 hours a year. The wife of the pilot reported that they purchased the airplane in 2002, and it has been parked in a hangar for a majority of their ownership. About 1.5 years leading up to the accident, the airplane had been undergoing an annual inspection and new paint, which was completed on February 24, 2017. When the maintenance was completed, the pilot ran the airplane's engine on the ground for about 45 minutes with no anomalies noted; the accident flight was the first flight post maintenance. According to a Continental Motors representative the fuel manifold valve is generally not disassembled by a mechanic in the field, and there are rarely issues with this engine component. If fuel issues are suspected, the troubleshooting section of the Continental Motors Standard Practices Manual (M-0) directs the mechanic to an isolated fix. If the problem is isolated to the fuel manifold, it is to be removed and either sent to an appropriate overhaul facility, or replaced by a new or rebuild from Continental Motors.

Probable Cause and Findings

A total loss of engine power due to internal corrosion of the fuel manifold valve. Also causal was the pilot's decision to return to the runway following the loss of engine power shortly after takeoff, and his exceedance of the airplane's critical angle of attack during the turn, which resulted in an aerodynamic stall.

 

Source: NTSB Aviation Accident Database

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