Date: 201411
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Daylight
Aircraft: Small Aircraft
Operator: Personal
Operating under: Part 91
Flight plan: None
Mission: Personal
Flight phase: Takeoff / Launch
Airspace: Class D ZZZ
ATC / advisory: Tower ZZZ
Aircraft component: Throttle/Power Lever
Component problem: Malfunctioning
Reporter organization: Personal
Reporter function: Pilot Flying; Single Pilot
Reporter qualification: Flight Crew Commercial
Human factors: Training / Qualification; Human-Machine Interface
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Landed in Emergency Condition; General Declared Emergency
Contributing factors: Aircraft; Human Factors; Procedure
Primary problem: Ambiguous

Narrative: After taxiing the plane to the hangar from recent repairs and annual inspection; the mechanic met me at the hangar to shuttle me back to my car. After he helped me push the plane into the hangar; he wanted to look at where the breather tube came out of the cowl. He had installed new scat tubing for the heater intake and he was concerned that the resulting positioning might rub against the new cowl. After the inspection; he suggested we tie wrap the breather tube in one more place to secure it to prevent it from rubbing on the new cowl. I placed a tie wrap that pulled side pressure on the tube pulling it toward the cowl opening and away from the metal. After I completed the work; the mechanic looked in and said we were good. The breather tube cleared the cowl.That weekend; I went to fly the plane for one more check flight after having it return to service. The run-up was good and magnetos; carb heat checked out. It was a windy day with winds 20-30kts. I was cleared for RWY17 a long taxi that allowed the oil to come to temperature.When I applied power for takeoff; the aircraft jumped into the air due to the wind. Since it was gusty; I was getting tossed about by the wind quite a bit. Halfway down the runway; I noticed that the plane wasn't climbing as expected (even with the substantial headwind) and I noticed that it wasn't developing full power. I verified the Carb heat was closed and throttle was full forward but the engine was not developing full takeoff power. By the time I realized I had an issue I was at the end of the runway. I was 200-300 feet over the end of the runway but the aircraft was not climbing or building speed. In fact; the plane was starting to settle and I was losing speed so I declared an emergency and returned to land on RWY 35. The landing (even with a substantial tailwind); was uneventful.When I got to the hangar; I discovered the problem. The tie wrap I had installed to put side pressure on the breather tube had continued tightening itself due to the engine vibration. The resulting over-tightened had pulled the breather tube into a position that blocked the forward movement of the throttle lever; preventing full advancement of the throttle. I cut the tie wrap and the breather moved back to its position and I regained full motion of the throttleWhen I went back to the plane to take pictures of the configuration; I tried to push the breather tube into a conflicting position with the throttle lever and it would happen. I can't replicate the fault on the ground; it does not create the interference. Pushing the breather tube to the side and securing it with the tie wrap does not create sufficient pressure or interference with the throttle motion. I suspect that what happened was that engine vibration overtighten the tie wrap through some kind of position shift. The more the engine vibrated; the more it pulled the breather tube into conflict with the throttle. This continued tightening is capable of pulling the breather tube into a position that interferes with the throttle. That is the only way I can speculate it got positioned in a way that it blocked the throttle lever. I called the mechanic over to the hangar to look at the problem with me and he asked me to ground the plane until he can reroute the breather tube on the other side of the scat tubing (where it is more distant from the throttle lever) and secure it with an Adel clamp. The FAA called me after the incident and assured me it was right to declare an emergency. After submitting the honest full disclosure above; he informed me I would be under investigation because I performed work as the owner installing the tie wrap and not documenting it in the log book. I am extremely concerned that overzealous investigator at the FSDO will lead to pilots like me being gun shy to declare emergencies because they immediately draw investigation.




Synopsis: Taking his Small Aircraft on a flight shortly after its annual inspection; the pilot found himself airborne but producing insufficient power to climb above ground effect. Pilot was forced to declare an emergency and land safely downwind on another runway.