Partial Panel Instrumentation Flight

CHAPTER THREE CHG 2

T-34C INSTRUMENTS

313.

PARTIAL PANEL INSTRUMENT FLIGHT

Partial panel instrument flight begins upon failure of the primary attitude instrument, the attitude

gyro. The flight must now be continued and the aircraft attitude controlled by referring to the

remaining instruments only. The loss of the gyro can occur from a failure of the gyro itself or

from an inverter (AC power) failure. In the event that the gyro failed due to an inverter failure,

partial panel flight would not be possible since the turn needle is also an AC powered instrument.

For training purposes, we will simulate partial panel by turning off the aft cockpit attitude gyro

and RMI. This will result in the loss of the attitude gyro, the RMI, and its associated single and

double navigation needles. We practice partial panel flight in the T-34 by simulating an inverter

failure since many fleet aircraft utilize a DC powered turn needle. In those aircraft, partial panel

flight is required with an AC power failure. The more likely scenario in the T-34 in which one

would encounter partial panel flight is with a singular failure of the attitude gyro itself.

When a gyro failure is recognized, transition to partial panel scan and immediately execute the

Emergency Procedures for inverter failure. Normally, this will restore power and the maneuver

may be continued. For partial panel training, after completing procedures and noting that the

OFF flag continues to indicate failure, smoothly level the wings with coordinated rudder and

aileron and reposition the nose to the straight and level flight attitude by crosschecking the VSI

and altimeter for level flight nose attitude and the turn needle and balance ball for a wings level

balanced flight condition. When established and trimmed in straight and level flight, continue

partial panel scan (Figure 3-14). Use the turn needle and balance ball for roll and yaw control

and the VSI and altimeter for pitch control. Then, make the following voice report to the

instructor: "I have a gyro failure; Emergency Procedures completed with negative results; on

partial panel scan."

With the failure of the primary attitude instrument, determine the nose and wing positions

through the indirect indications of the turn needle and balance ball, airspeed indicator, altimeter,

and vertical speed indicator. These instruments now become attitude "control" instruments vice

crosscheck instruments. Because of the loss of the attitude gyro's direct indication of our

relationship to the horizon, we must incorporate a certain amount of "feel" in our control

pressures in order to establish our nose and wing positions. Necessary control pressures will be

recognized through experience in a particular type of aircraft. Excellent trim is mandatory in

partial panel in order to relieve these control pressures so that the aircraft will remain in its set

attitude.

3-38 BASIC INSTRUMENTS FLIGHT PROCEDURES