The loosest slots in town - aircraft gauges

Approach, Nov, 2002 by Jerry Stokes

We were recalled early from an uneventful AEW mission. As CATCC vectored us for descent to a night approach, we ticked off the approach checks. Juggling the checklists and dumping fuel, we kept in step with the Hummer dance as several cloud layers disappeared above us in darkness. We weren't sure if we could squeeze off the gas in time, so we slowed through gear speed to dirty-up at six miles.

The gear and flap indicator came alive. I covered the gear-handle light with my hand, then watched the wheel symbols appear like slot-machine fruit in the gauge. I glanced at the altimeter to back up the pilot, then looked at the gear indicator, expecting the Goodyear jackpot. Instead, the right main gear remained barber-poled, while the eerie red glow of the gear handle continued to light the cockpit. I waited another second and looked again at the gauge, then to the AOA indexers, which were dark. The gear-handle light continued to burn brightly. The pilot secured the fuel dumps slightly above max trap, as I advised approach we had a gear malfunction and requested a rep.

The aircraft had a long history of barber-poled indications with the right main gear and had been drop-checked several times over the previous months. Each successive drop-check involved increasingly intense searches for causes. Findings included worn wires, slightly misaligned switches, and bent contacts. These problems quickly were repaired. Drop-checks were completed, and the discrepancy was signed off each time.

I had had a right main barber-pole in the aircraft on the beach a few weeks earlier. I checked the hydraulic pressure and the gear and flap gauge, applied positive and negative acceleration, and tried to yaw the aircraft--still with no down indication. I even cycled the landing gear. On that occasion, the gear went up and locked, then came down with a good down-and-locked indication. I talked with other pilots in the squadron who had the same experience with the aircraft, and, in every instance, cycling the gear provided a positive down-and-locked indication.

We continued upwind in the darkness, checking hydraulic pressures and the gear-indicator gauge, as the CICO pulled up dirty-bingo numbers to the beach--160 miles to the west. Our rep came up as the pilot began to apply G and yaw to the aircraft. Horsing the aircraft around on downwind, however, failed to clear the barber-pole. We agreed with the rep to cycle the gear handle.

Fully expecting the gear indication to clear itself. I stared in disbelief as the pilot raised the gear handle. The gearhandle light remained bright red, and the gear indicator continued to show left main and nosegear down-and-locked with a barber-pole on the right main. The CICO confirmed the right main still appeared down-and-locked, and the pilot saw the left main still reflecting the anti-collision strobe. I reached over and gave the gear handle a forceful shove to make sure it was up all the way. The warm fuzzy feeling that I was dealing with a familiar problem began to vanish. In every previous incident, I had suspected a switch or indicator problem. Now, I wondered about some kind of structural or mechanical problem.

After again consulting the PCL, we reasoned the ultimate goal was to get three gear down-and-locked. Lowering the gear handle again would get us closer to that goal, and it couldn't make matters any worse. After lowering the gear handle, the red light continued to burn, the indexers remained dark, and the gear gauge continued to indicate down for the left and nose gear and barber-pole for the right main.

The CICO reported the right main-gear assembly seemed to move slightly toward the typical down-and-locked alignment. We looked at our fuel and now were within 500 pounds of our calculated dirty-bingo state. The acceleration and G application with the gear down had eaten into our reserve faster than we anticipated. We referenced the PCL and then accelerated to provide additional airflow to force the right main gear, while the pilot actuated the blow-down handle on the emergency gear--nothing happened. The CICO reported no change in gear-linkage geometry, and our indications remained the same in the cockpit.

I advised the rep of our negative results and flipped to the emergency-action matrix for the landing gear to prepare for a "One Main Gear Unsafe or Up" landing. Since we had a suitable divert field with arresting gear, and I wanted to forgo any possibility of a gear strut collapsing during rollout on the CV, I advised approach I was within five minutes of bingo fuel. I also said we were climbing toward the divert. I discussed our intentions with the rep, and the CICO alerted the divert field we were inbound for an arrested landing.

I read aloud the procedures outlined in the PCL as we climbed into a 40-knot headwind. We already had dumped or burned as much gas as possible to reduce our weight. The hook was down, and we were en route to a field arrestment.

The major topic of discussion was whether to secure the right engine before landing. My first response was a definite "yes." Normally, I would have considered the possibility of engine failure very remote, but our squadron had experienced two non-mitigated, first-stage-compressor failures the previous month. I had aborted a CQ mission two weeks earlier when my left engine gave up the ghost. The question we posed was, "Which is the smaller risk: collapsing the right landing gear and inflicting severe FOD damage from a spinning prop, or losing the left non-mitigated engine after shutting down the right engine for approach?"