CHAPTER 13. Abnormal and Emergency Procedures

Emergency Descents

An emergency descent is a maneuver for descending as rapidly as possible to a lower altitude or to the ground for an emergency landing. The need for this maneuver may result from an uncontrollable fi re, avoidance of other aircraft, weather, or any other situation demanding an immediate and rapid descent. The objective is to descend the aircraft as quickly as possible within the structural limitations of the aircraft. Simulated emergency descents should be made in a turn to check for other air traffi c below and to look around for a possible emergency landing area. A radio call announcing descent intentions may be appropriate to alert other aircraft in the area. When initiating the descent, a bank angle of approximately 45° to 60° should be established to maintain positive load factors (“G” forces) on the aircraft.

Generally, the steeper the bank angle is, the quicker the descent is. But caution should be exercised with steep bank angles for extended periods because the high G forces and rotation can cause disorientation or motion sickness, which might make matters worse. The manufacturer’s bank and speed limitations should not be exceeded.

Emergency descent training should be performed as recommended by the manufacturer, including the confi guration and airspeeds. The power should be reduced to idle. The pilot should never allow the aircraft’s airspeed to surpass the never-exceed speed (VNE) or go above the maximum maneuvering (VA) speed, as applicable. In the case of an engine fi re, a high airspeed descent could extinguish the fi re. The descent should be made at the maximum allowable bank angle and airspeed consistent with the procedure used. This provides increased loads and drag and therefore the loss of altitude as quickly as possible. The recovery from an emergency descent should be initiated at an altitude high enough to ensure a safe recovery back to level fl ight or a precautionary landing.

When the descent procedure is established and stabilized during training and practice, the descent should be terminated. For longer descents, alternating turn directions should be used so the pilot does not become disorientated. Prolonged practice of emergency descents should be avoided to prevent excessive cooling of the engine cylinders. [Figure 13-7]

Infl ight Fire

A fi re in fl ight demands immediate and decisive action. The pilot must be familiar with the procedures to meet this emergency as contained in the AFM/POH for the particular aircraft. For the purposes of this handbook, infl ight fi res are classifi ed as: engine fi res and electrical fi res. If a fi re extinguisher is installed on the WSC aircraft, the passenger should be briefed on its use and the pin should be connected to the extinguisher by a lanyard so it cannot be dropped into the propeller, creating a worse situation.

Engine Fire

An infl ight engine fi re is usually caused by a failure that allows a fl ammable substance such as fuel, oil, or hydraulic fl uid to come in contact with a hot surface. This may be caused by a mechanical failure of the engine itself, an enginedriven accessory, a defective induction or exhaust system, or a broken line. Engine fi res may also result from maintenance errors, such as improperly installed/fastened lines and/or fi ttings, resulting in leaks.

Engine fires can be indicated by smoke and/or flames coming from the engine area. They can also be indicated by discoloration, bubbling, and/or melting of the engine cowling skin in cases where fl ames and/or smoke are not visible to the pilot. By the time a pilot becomes aware of an infl ight engine fi re, it usually is well developed. Unless the aircraft manufacturer directs otherwise in the AFM/POH, the fi rst step after discovering a fi re is to shut off the fuel supply to the engine (if so equipped). The ignition switch should be left on in order to use up the fuel that remains in the fuel lines and components between the fuel selector/shutoff valve and the engine (if equipped with an electric fuel pump). This procedure may starve the fi re of fuel and cause the fi re to die naturally. If the fl ames are snuffed out, no attempt should be made to restart the engine.

If the engine fi re is oil-fed, the smoke is thick and black, as opposed to a fuel-fed fi re which produces bright fl ames with less smoke.

Some light aircraft emergency checklists direct the pilot to shut off the electrical master switch. However, the pilot should consider that unless the fi re is electrical in nature, or a crash landing is imminent, deactivating the electrical system prevents the use of radios for transmitting distress messages and also causes air traffi c control (ATC) to lose transponder returns.

The pilot must be familiar with the aircraft’s emergency descent procedures and remember that:

  • An engine fi re on a WSC aircraft means the fl ames are going to the rear of the aircraft where minimum components are exposed. If the BPS is used, it would change the direction of the fl ames, possibly setting the wing and/or fuselage on fi re. The fl ames could also burn the parachute line, creating worse problems.
  • The aircraft may be structurally damaged to the point that its controllability could be lost at any moment.
  • The aircraft may still be on fi re and susceptible to explosion.
  • The aircraft is expendable—the only thing that matters is the safety of those on board.
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