AFH 5-26

Weight and Balance Requirement Related to Spins In airplanes that are approved for spins, compliance with weight and balance requirements is important for safe performance and recovery from the spin maneuver. Pilots should know that even minor weight or balance changes can affect the airplane’s spin recovery characteristics. Such changes can either degrade or enhance the spin maneuver and/or recovery characteristics. For example, the addition of weight in the aft baggage compartment, or additional fuel, may still permit the airplane to be operated within CG, but could seriously affect the spin and recovery characteristics. An airplane that may be difficult to spin intentionally in the utility category (restricted aft CG and reduced weight) could have less resistance to spin entry in the normal category (less restricted aft CG and increased weight). This situation arises from the airplane’s ability to generate a higher AOA. An airplane that is approved for spins in the utility category but loaded in accordance with the normal category may not recover from a spin that is allowed to progress beyond one turn. Common Errors Common errors in the performance of intentional spins are: 1. Failure to apply full rudder pressure (to the stops) in the desired spin direction during spin entry 2. Failure to apply and maintain full up-elevator pressure during spin entry, resulting in a spiral 3. Failure to achieve a fully-stalled condition prior to spin entry 4. Failure to apply full rudder (to the stops) briskly against the spin during recovery 5. Failure to apply sufficient forward-elevator during recovery 6. Waiting for rotation to stop before applying forward-elevator 7. Failure to neutralize the rudder after rotation stops, possibly resulting in a secondary spin 8. Slow and overly cautious control movements during recovery 9. Excessive back-elevator pressure after rotation stops, possibly resulting in secondary stall 10. Insufficient back-elevator pressure during recovery resulting in excessive airspeed Spiral Dive A spiral dive, a nose-low upset, is a descending turn during which airspeed and G-load can increase rapidly and often results from a botched turn. In a spiral dive, the airplane is flying very tight circles, in a nearly vertical attitude and will be accelerating because it is no longer stalled. Pilots typically get into a spiral dive during an inadvertent IMC encounter, most often when the pilot relies on kinesthetic sensations rather than on the flight instruments. A pilot distracted by other sensations can easily enter a slightly nose-low, wing-low, descending turn and, at least initially, fail to recognize this error. Especially in IMC, it may be only the sound of increasing speed that makes the pilot aware of the rapidly developing situation. Upon recognizing the steep nose-down attitude and steep bank, the startled pilot may react by pulling back rapidly on the yoke while simultaneously rolling to wings-level. This response can create aerodynamic loads capable of causing airframe structural damage and/or failure. The following discussion explains each of the five steps a pilot should use to recover from a spiral dive: 1. Reduce power (throttle) to idle. Immediately reduce power to idle to slow the rate of acceleration. 2. Apply some forward-elevator. Prior to rolling the wings level, it is important to unload the G-load on the airplane (“unload the wing”). This is accomplished by applying some forward-elevator pressure to return to about +1G. Apply just enough forward-elevator to ensure that you are not aggravating the spiral with aft- elevator. While generally a small input, this push has several benefits prior to rolling the wings level in the next step – the push reduces the AOA, reduces the G-load, and slows the turn rate while increasing the turn radius, and preventing a rolling pullout. The design limit of the airplane is exceeded more easily during a rolling pullout, so failure to reduce the G-load prior to rolling the wings level could result in structural damage or failure. 3. Roll to wings level using coordinated aileron and rudder inputs. Even though the airplane is in a nose-low attitude, continue the roll until the wings are completely level again before performing step four. 4. Gently raise the nose to level flight. It is possible that the airplane in a spiral dive might be at or even beyond VNE (never exceed speed) speed. Therefore, control inputs are made slowly and gently at this point to prevent structural failure. Raise the nose to a climb attitude only after speed decreases to safe levels. 5. Increase power to climb power. Once the airspeed has stabilized to VY, apply climb power and climb back to a safe altitude. In general, spiral dive recovery procedures are summarized in Figure 5-18.