TD 21

Question 1

Aerobic Flight Maneuvers

Answer 1

Aerobic maneuvers are prohibited. Aerobic flight is defined to be any intentional maneuver involving an abrupt change in aircraft attitude, an abnormal attitude, pitch angle greater than 30 degrees or roll angles greater than 60 degrees, or abnormal acceleration not necessary for normal flight.

Question 2

Lightning Strike

Answer 2

WARNING
Avoid flight in or near thunderstorms, especially in areas of observed or anticipated lightning discharges.

NOTE
Abnormal operating noises almost always accompany rotor damage, but loudness or pitch is not valid indications of the degree of damage sustained.

If lightning strike occurs, or is expected, the following precautions are recommended to minimize further risk:

    1. Reduce airspeed as much as practical to maintain safe flight.
    2. Avoid abrupt control inputs.

Question 3

Landing in Trees

Answer 3

A landing in trees should be made when no other landing area is available. In addition to accomplishing engine malfunction emergency procedures, select a landing area containing the least number of trees of minimum height. Autorotate with the throttle closed using the following procedure:

    1. Airspeed- Minimum at treetop level
    2. Descend- vertically into trees
    3. Collective- apply remaining collective prior to blades entering trees

Question 4

Hydraulic Power Failure

Answer 4

A. The first indication of hydraulic boost failure will be an increase in the force required for control movement; feedback forces will be noticed as well as rate limiting. Control motions will result in normal flight reactions in all respects, except for the increase in force required for control movement. In the event of hydraulic power failure, proceed as follows:

    1. Airspeed- adjust as necessary to attain the most comfortable level of control movements.
    2. HYD BOOST circuit breaker- OUT. Check for restoration of hydraulic power.

B. If hydraulic power is not restored:
1. HYD BOOST circuit breaker- IN.

WARNING
Do not return the HYDR SYSTEM switch to the ON position for the remainder of the flight. This prevents any possibility of a surge in hydraulic pressure and the resulting loss of control.

2. HYDR SYSTEM switch ─ OFF.
3. Land as soon as practicable at an area that will permit a run-on landing.

Question 5

Hypoxia

Answer 5

Hypoxia is defined as the state of oxygen deficiency in the blood cells and tissues enough to cause impairment of function.

Types of hypoxia:

    1. Hypoxic- altitude, when there is not enough oxygen in the air or decreasing atmospheric pressure prevents diffusion of oxygen into the bloodstream.
    2. Hypemic- blood loss, anemia, smoking, reduction in the blood’s oxygen carrying capacity
    3. Stagnant- heart attack, pooling from G forces, blood’s oxygen carrying capacity is adequate but circulation is not
    4. Histotoxic- alcohol, interference with the use of oxygen by body tissues

Stages of hypoxia:
- Indifference stage
Surface-10,000; night vision affected at 4,000’, effect of hypoxia increased with self imposed stressors
- Compensatory stage
10,000-15,000; effects on CNS, impaired efficiency is apparent after 10-15 minutes
- Disturbance stage
15,000-20,000; physiological responses can’t compensate for oxygen deficiency, LOC, loss of senses (vision first, hearings last), reduced mental processes, unusual personality traits, reduced psychomotor functions, cyanosis
- Critical stage
20,000+; 3-5 min = judgement and coordination lost, mental confusion, dizziness, incapacitation, and LOC

Treatment:
100% oxygen and descend to below 10,000’

Prevention:
Prevention methods include limiting time at altitude, using supplemental O2, and pressurizing the cabin.
Supplemental oxygen- 
>10,000’ for > 1 hour
>12,000’ for >30 min
>14,000’ for any amount of time