Page 14 - July24T

Owners Troy and Sherry Welch enjoy an evening sunset flight in their Twin Navion over central Texas. [Jack Fleetwood]
Rear-seat passengers enter with ease. But continuing forward requires some contorting in order to squeeze between the pilot seats while also maneuvering around the sizable power quadrant. The alternate method of stepping di- rectly onto the pilot seat, then sliding down into position, is only marginally easier, as the windshield frame comes too far aft to allow you to simply drop in vertically. Yet, the slightly awkward entry is no worse than so many other airplane types, including many cabin- class twins. Once in position, the pilot work station is very comfortable. Vis- ibility for all occupants is excellent. The seat pans are well above the level of the wing, putting your sight line both high above the ground and above most of the airframe, too. Unlike most low-wing piston twins, neither the en- gine nacelles nor the long nose restrict visibility significantly.
The panel layout of Welch’s steed is still a little old school. The radio stack is far left and partially blocked from view by the left yoke (especially for the right-seater). However, the f light instruments have been updated into a standard 6-pack arrangement with a modern Garmin G5 attitude indi- cator. Mag switches and the hydrau- lic pump control are a bit hidden to the right of the power quadrant. The quadrant itself appears a bit busy, but it’s actually very well organized. As with many twins of the era, the throttles are centered, while the prop controls are to the left. The quadrant also features starter, primer, and fuel pump switches, plus f lap, gear, trim, and carb heat controls.
12 • TWIN & TURBINE / July 2024
The Personality of N108N
Toggling the 3-position electric switch left and right to prime the car- bureted engines makes hot or cold starts predictable. Taxiing presents no unusual challenges, with responsive braking and steering and the availabil- ity of differential thrust if extra tight turns are necessary. Run-up and pre- takeoff checks are standard, as well. Check mags, carb heats, vacuum and hydraulic pumps, and cycle the props.
Like in all U.S. aircraft of this era, speeds are all in MPH. Initially, we were relatively light with only about 50 gallons of fuel, two adult males, and about 100 pounds of bags in the aft compartment. But, the afternoon temps in southern Arizona were in the high 80’s. Vmc (minimum control speed, single-engine) is marked as the lower redline of 86. Vyse is 102, but no blue line denotes it on the ASI. How- ever, the Navion’s big wing and thick airfoil are ready to fly before reaching Vmc. So, one can be patient and al- low speed to build in a longer ground roll, or level in ground effect briefly to allow speed to accelerate past Vmc and towards Vyse before climbing. I did a little of both, and in short order, Troy and I were headed southwest for maneuvers enroute to Gila Bend Municipal Airport (E63).
Basic air work in the ‘55 was sedate. Stability abounds, making steep turns, slow f light, and stalls absolutely pre- dictable. The big light twin (an oxy- moron that feels totally appropriate) is surprisingly light on the controls but very well harmonized. However, trimming can be cumbersome. Both
rudder and elevator trims are oper- ated via small left/right cranks on the lower power quadrant. Rudder trim is intuitive in this arrangement. Elevator trim is not. Clockwise for nose down, counter-clockwise for up. In practice, it’s an exercise in gauging reaction to your input versus consciously crank- ing in the correct direction. I’m re- minded of old Pipers with the trim crank on the ceiling. Each time a new input is needed, everyone seems to turn it the wrong way at first.
Trimming nit-picks aside, we were soon exploring single-engine opera- tions. The T-Nav’s critical engine is on the left, as in most non-counter- rotating light twins. But, because the engines are only rated at 170hp each, this “criticality” is less noticeable than in more powerful twins. With the left engine at zero-thrust, we could easily maintain 200-300 FPM climbs well be- low full power on the operating engine. This was also easy to manage without adding rudder trim. With full power on the right engine only and trimmed out, 500+ FPM was sustainable right to our cloud-limited altitude of 4,500’ or so. The literature says the Riley ‘55’s single-engine service ceiling at MGW is 6,000 feet. Of course, that’s likely a standard temperature calculation. Because we were somewhat altitude- limited by cloud coverage, we didn’t explore Vmc down to directional con- trol loss. However, the single-engine flying we worked on made it obvious that the rudder was huge and very effective.
For pattern work, Welch’s preferred method is to slow below the common