Aircraft Accident/Incident Report

Marana, Arizona 85653
Sunday, November 12, 2000 10:50 MST

The airplane made a forced landing in an open desert area and came to rest inverted after colliding with desert brush. Earlier that morning, a 20-minute flight from home base to a local airport was conducted for the purpose of flight training for the pilot's son. Prior to the return flight, the son informed his father that during his flight the engine would balk, sputter, and cough every time he added power. When asked by his father if he was engaging the throttle too quickly, the son replied that he did not. The CFI was asked if he had noticed any problems with the engine. He replied that there was nothing unusual experienced with the engine. No discrepancies were noted during the taxi, takeoff roll, or initial climb out. About 15 minutes into the flight the pilot noted a drop in rpm. He made several unsuccessful attempts to troubleshoot the problem. When he applied carburetor heat, there was a further loss of rpm. The external examination of the engine disclosed no discrepancies. The engine was test run. The first engine start was unsuccessful. Ether was sprayed on the intake filter and several more attempts were made to start the engine. The engine would start, but would only run for 10 seconds during those attempts. The carburetor was removed and inspected. Fuel was observed in the bowl with unrestricted movement of the floats, and the main jet appeared free of debris. The carburetor was sent to the manufacturer for further examination. During the bench test when fuel was initially applied, it flooded the carburetor. When the outside of the carburetor was manually tapped the flooding stopped. No further discrepancies were noted with the bench test. An internal examination revealed that the float valve retractor clip was adjusted too loosely on the float and needle to ensure a positive retraction of the needle. This allowed for the clip to stick in the down position and allowed an increased amount of fuel to enter the carburetor. A blue silicone substance was found around the accelerator pump sump retainer and sump. The accelerator pump discharge check valve was leaking and not sealing properly. No further discrepancies were noted.

The partial loss of engine power during cruise flight due to an improper maintenance adjustment to the float valve retractor clip of the carburetor. Factors were the lack of suitable terrain for a forced landing and high vegetation.