PA-28R Cherokee Arrow All Series
Flight Crew Commercial; Flight Crew Flight Instructor; Flight Crew Instrument; Flight Crew Multiengine
Flight Crew Last 90 Days 75; Flight Crew Total 1540
Aircraft Equipment Problem Less Severe; Inflight Event / Encounter Fuel Issue
Flight Crew Rejected Takeoff; General Maintenance Action
Aircraft
CFI candidate was previously flying with a different instructor in the Arrow (PA-28R-200) at our flight school for the commercial pilot certificate. Plane was topped off with fuel just prior to our flight; and fuel was drained. We did taxi and runup normally (although previous instructor had CFI candidate use a different method than the checklist to start the engine; by using full throttle to prime the engine and shutting off fuel pump before starting). After runup; CFI candidate performed pre-takeoff checklist. During pre-takeoff checklist; CFI candidate changed fuel from right tank to left tank. I told her she wasn't 'wrong' to do so (so long as fuel was properly drained during preflight); but normally we don't change tanks then because if there is a problem with the fuel or contaminants or water in the other tank; we don't want to find that out during our takeoff climb. We got to the end of the runway and gave full throttle; powered up normally; and then as we were rolling lost a significant amount of power (on the order of losing 50%-75% of our power). Exited the runway and taxied back to base. Mechanic did thorough and extended runup and said everything is OK; probably just some water in the fuel (on several previous flights; I have found small amounts (2-3 tablespoons?) of rust-colored water from the left tank; probably came from the fuel truck and is difficult to remove from the airplane. From what I can tell; this plane's left tank is the only plane in our fleet that has this rust-colored water coming from it; albeit small amounts and only rarely). Chief of flight operations took the plane for a test flight after the mechanic's extended runup and declared everything OK. Question - if there is some water from the fuel truck in the left tank; how can we remove it if repeated draining don't remove it? Corrective actions - don't switch tanks after runup; and make sure to drain at least a full fuel cup at each fuel drain during preflight.
Piper PA-28 flight instructor reported an aborted takeoff due to loss of power.