The plan was to fly to some inland airports where the reported weather was VFR. At the first one, wed shoot a practice ILS and fly the published missed approach to a hold at the local VOR. From there we would fly a practice VOR approach to another local airport and finish up with the LDA approach into our home base.
As sometimes happens, I got held up at the office and arrived late. In order to help keep us on schedule, my CFI pre-flighted outside the twin while I set up inside. The run-up was smooth and we departed approximately 40 minutes after our planned departure time.
On climb-out, the airplane had a slight tendency to roll right. It was nothing I couldnt handle and we attributed this to being the first flight after a lengthy maintenance period.
Boy, I thought, it sure is unusually quiet up here. A couple of radio checks confirmed that the number two radio had given up the ghost. Switching to the number one radio, I checked in and received a tongue lashing from ATC. A new vector had us intercepting the airway to our original destination with a frequency change and a phone number to call when we landed-ATC was not impressed with how quickly I had deduced a radio failure.
Instead of flying the published missed approach, we landed at our first airport around dusk. We parked on the ramp and I called ATC; but not before noticing a substantial amount of fuel coming from the right outboard fuel vent. ATC delivered a big lesson on lost-communication procedures.
Of course, at that point it was too late to complete our planned fight, so we decided to fly back to base. Taxiing to the active runway, we were given a 10-minute hold for IFR release and took our time with the run-up procedure. Come on departure, were getting asphyxiated by the smell of fuel, we were thinking, although each of us figured it was what you always smelled in these older airplanes.
Finally we launched into an evening sky. The slight tendency to roll right had now become more pronounced, which had both of us monitoring engine instruments and the starboard engine for signs of propeller problems or any other explanation. Soon, we were in solid IMC (and at night); the tendency of the aircraft to roll right became even more pronounced. My instructor took the controls for a moment and acknowledged the heavy wing, but no yaw. Must be asymmetric thrust. He turned on the fuel pumps just in case.
The first approach to home base was aborted and, coming back for another try, it now took both hands to counter the right roll. Plus, we both had our hands full with the radios. Finally, we broke out with the airport off the nose. The landing was nowhere near the greaser it had been at the first airport, but as my flight instructor said, it wasnt bad considering the heavy wing I was fighting.
Once parked and out of the airplane, we noticed a lot of fuel coming from the inboard fuel vent on the right side. What could it be? There must be a fuel pressure problem, we thought. I stepped up and opened the fuel cap on the inboard tank and was subsequently drenched with the 100LL fuel that immediately erupted from the tank. Yep, there was definitely a fuel pressure problem.
As it turned out, the prolonged maintenance interval was to replace an engine. The crossfeed valve had been left on after testing to ensure it functioned properly. Instead of those pesky mechanics screwing up, it was a pilot rushing through a checklist and allowing himself to get distracted. As the problem got worse, our troubleshooting process left a lot to be desired. Enough clues were there for two competent pilots to discern what was going on had we both not been in denial. A progressively worsening roll right without yaw; fuel venting from the tank selected; a strong fuel odor while awaiting release. What else did we need? We checked everything except the simplest explanation, a fuel imbalance.
In our haste to launch, the distraction of a radio failure and my first copy-this-number clearance, I had left on the crossfeed during the entire flight. We were pumping about 75 pounds of fuel per hour from the left side of the airplane to the right. Once the tanks filled, the fuel simply vented overboard. We were lucky enough to get back to home base in the nighttime IFR conditions before we ran the left tanks completely dry and/or ran out of aileron authority to counter the right roll.
During both pre-launch checks and run-ups I had touched the crossfeed and told myself it was off, without visually checking it was in that position. After all, nobody ever turns the crossfeed on unless there is a problem.
We were lucky this time and have both learned an important lesson about not forgetting that the simplest explanation for a problem is usually the right one. Now I will always verify control positions visually rather than rely simply on touch. Sometimes our memory of where the control should be located is not always completely accurate.