CHAPTER 6
ANSWERS TO REVIEW QUESTIONS
A6-1. 14.7 psi
A6-2. Breathing
A6-3. The human body tends to burst. In some cases, blood vessels near the surface
may burst, causing hemorrhages in the ears, eyes, and breathing passages.
A6-4. 1. The cabin must be designed to withstand the necessary pressure differential.
This is primarily an airframe engineering and manufacturing problem.
2. There must be a means of limiting the maximum pressure differential to which
walls will be subjected. This is provided by the cabin safety valve.
3. The aircraft must have an adequate supply of compressed air. This is provided
through the compressor section of the jet engine. A separate compressor or
supercharger is used on aircraft having reciprocating engines. On all jet
aircraft, the air is taken directly from the compressor section of the jet engine.
This is generally referred to as bleed air.
4. There must be a means of cooling the bleed air before it enters the cabin. This
is provided by an aircraft refrigeration unit.
5. There must be a means of controlling the cabin pressure. This is provided by
the cabin pressure regulator, which regulates the outflow of air from the cabin.
A6-5. The environmental control systems of most aircraft include cabin
air-conditioning and pressurization, equipment cooling, defogging, windshield
washing and rain removal, and equipment pressurization subsystems.
A6-6. The name air cycle or air-to-air comes from the principle of cooling the air
without the use of refrigerants by compression and expansion of bleed air.
A6-7. No. 3
A6-8. Two flow-limiting venturis
A6-9. 70 percent
A6-10. Temperature controller
A6-11. Turbine refrigeration unit
A6-12. Automatic and manual
A6-13. Pressurizing the cockpit/cabin area
A6-14. By the use of seals around tubing, ducting, bolts, rivets, and other hardware that
pass through or pierce the pressure tight area. All panels and large structural
components are assembled with sealing compounds.
A6-15. Cabin pressure regulator
A6-16. Isobaric
A6-17. When returning to the normal mode from the dump mode or during a rapid
descent in excess of 4,000 feet per minute.
A6-18. 5,000 feet
6-20
