Type training · Boeing 737 Classic B1.1 · ATA 21

Boeing 737 Classic B1.1: Air Conditioning and Pressurization (ATA 21)Type training questions & answers

Packs and ram air, temperature control and trim air, equipment cooling, and both cabin pressure control systems.

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Sample Air Conditioning and Pressurization questions with answers

Three questions from the free preview. Think of your answer first, then open the explanation.

  1. 1.What are the three main parts of the cooling equipment in each 737 Classic air cycle system?

    • A.Primary HX, secondary HX, ACM
    • B.Precooler, ACM and the mix manifold
    • C.Ram air fan, condenser and reheater
    Show answer and explanation

    Correct answer: A. Primary HX, secondary HX, ACM

    Each air cycle system has a primary heat exchanger, a secondary heat exchanger and an air cycle machine, in a bay under the centre fuselage. Ref 737-300/400/500 AMM 21-51-00.

  2. 2.Where are the 737 Classic air conditioning packs installed?

    • A.In the forward cargo hold, under its ceiling
    • B.Bays either side, under centre fuselage
    • C.In the tail cone, aft of the pressure bulkhead
    Show answer and explanation

    Correct answer: B. Bays either side, under centre fuselage

    The air cycle equipment is in equipment bays on each side of the airplane centreline at the underside of the centre fuselage. Ref 737-300/400/500 AMM 21-51-00.

  3. 3.Why does the 737 Classic water separator 35°F control system bypass warm air?

    • A.To raise cabin temperature fast
    • B.To cool the ACM bearings
    • C.To stop ice in the separator
    Show answer and explanation

    Correct answer: C. To stop ice in the separator

    When turbine discharge air is at 35°F or less, the 35°F valve opens and adds warm air so moisture does not freeze on the coalescer bag. Ref 737-300/400/500 AMM 21-51-00.

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Part of the Boeing 737 Classic B1.1 type course

One chapter of the Boeing 737 Classic B1.1 type course question bank, for the 737-300/400/500 with CFM56-3 engines, written in our own words for revision. Your type course and the aircraft maintenance manual stay the authority: limits and procedures can differ between airframes and operators.

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