737 equip cooling
 

Q. Aircraft climbs and fails to pressurize.Both OFF lights are ON for equip cooling fans in both NORMAL and ALTN positions.Might you expect this due to a lack of airflow?

Q. Aircraft undergoes a full check of one of its doors prior departure.Structural integrity chk and full diff pressure check.Can you pls detail how this check is accomplished?Are any circuit breakers pulled as part of the procedure?

Not sure what you are asking............. but to carry out a ground pressurization check on a 737 classic.... All doors and hatches shut.

Run an engine..... ( as apu rarely has enough air avail to get to max diff ) bleed air on , at least one pack running.

select Man ( AC or DC ) on press. control panel............toggle climb/descend switch to descend (closing the outflow valve )monitoring the cabin VSI and diff press ............easy ! listen to the creeks and groans from the fuselage as it pressurizes......often the VSI suddenly jumps as various seals get blown into place and the fuselage drains close..........

take it slowly so as not to hurt your ears/ sinuses :cool: :cool:

Equip cooling - lack of airflow - split duct, fans or low flow sensor.
Low flow sensor ofter gets dirty & indicates low flow despite a good flow. Take low flow sensor out & clean. While cleaning you should be able to fee airflow from the sensor fitting. Check for both norm & alt.