Reno, NV, USA
N1YZ
Rouse Glasair III
The pilot reported that as he turned toward the airport to land, black smoke was coming from under the cowling. The airplane was losing power, airspeed, and altitude; however, he was able to maintain enough airspeed to clear a cliff before touching down short of the runway. The airplane encountered uneven terrain, and the landing gear sheared off. An inspection of the engine revealed that all spark plugs and the entire exhaust path were very sooty, which corresponded to rich operation. Examination of the fuel servo revealed that it had excessively worn throttle/mixture linkage arms and pins. In addition, the mixture control linkage spring washer was missing. This linkage section is vital to maintaining the correct flows at throttle open positions, and the play noted was excessive.
On August 16, 2008, about 0750 Pacific daylight time, an experimental Glasair III, N1YZ, collided with terrain during a forced landing near Reno/Stead Airport, Reno, Nevada. The owner was operating the airplane under the provisions of 14 Code of Federal Regulations (CFR) Part 91. The certificated airline transport pilot was not injured; the airplane sustained substantial damage to the fuselage. The cross-country personal flight departed Minden, Nevada, at an undetermined time with a planned destination of Reno. Visual meteorological conditions prevailed, and no flight plan had been filed. The pilot stated that he extended the downwind for landing on runway 26. As he turned to land, black smoke was coming from under the cowling. He said that the airplane was losing power, airspeed, and altitude; however, he was able to maintain enough airspeed to clear a cliff and subsequently land short of the runway. The airplane encountered uneven terrain, and the landing gear sheared off. During the post accident engine inspection, the top spark plugs were removed. No mechanical deformation was noted, however, the plugs were sooty, which corresponded to a rich operation according to the Champion Aviation Check-A-Plug AV-27 Chart. The exhaust path was sooty as well. The crankshaft was manually rotated. The valves moved approximately the same amount of lift in firing order. The gears in the accessory case turned freely. Thumb compression was obtained on all cylinders in firing order. Both magnetos produced spark at all ignition wires in firing order. The fuel injection servo, fuel manifold valve, and fuel injector lines were retained for further examination. During removal, fluid that smelled like aviation gasoline drained from the line from the servo, and from the servo itself. The mixture control moved from stop to stop. During the examination of the fuel control, flow divider, and nozzle tests at Pacific Continental Engines, test personnel noted the following results. The fuel servo flows in pounds per hour (pph) were within acceptable serviceable limits as recommended by Precision Airmotive: 0" at idle cut off - 3 pph 0" - 40 pph 3.6" - 74 pph 15.8" - 165 pph Pacific Continental Engines personnel noted that the fuel servo RSA-10ED, serial number 64893, part number 2524491-8, had excessively worn throttle/mixture linkage arms and pins. In addition, the mixture control linkage spring washer was missing. They indicated that this linkage section is vital to maintaining the correct flows at throttle open positions. They said that the play was excessive. Test personnel inspected the flow divider, serial number M114, part number 79007, and found it acceptable. They did not record flows, but they noted even distribution. The nozzle flows in pph at 12.5 pounds per square inch (psi) were: VE1 = 40 pph VE2 = 36.5 pph (poor spray pattern noted - intermittent) VE3 = 40 pph VE4 = 40 pph VE5 = 40 pph VE6 = 40 pph Test personnel noted that the nozzles were manufactured by GAMI, but there was no documentation in the logbooks. GAMI did not recognize the airplane's registration number when the test personnel inquired. GAMI keeps a record of nozzle kits sold against a registration number (especially if it is under their STC application).
The excessively worn throttle/mixture linkage arms and pins and a missing mixture control linkage spring washer, which resulted in a loss of power due to an excessively rich mixture.
Source: NTSB Aviation Accident Database
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