B737-800 captain raises some interesting points about allowing the crew to placard a single pack con...

Narrative:

Departing on an out and back the first officer tested the master caution system and received a pack light. The pack light went out on reset. With the information we have this indicates a single pack controller failure. This is crew placardable with MEL 21-20a. Although I do not know how to tell if we use a) primary or B) secondary for the placard. We completed the turn and were to keep the aircraft for our third leg. Maintenance came to the plane to make a balancing entry and performed a bite check. The bite check indicated a pack temperature controller failure which was placarded with 21-20a. My problem now is that although we are given the ability to placard; the systems knowledge from the MEL book is not comprehensive enough to account for the other problems that can be revealed during a bite check. Without being able to diagnose the problem; I do not believe we should be placarding the pack light that resets. I have also learned that when maintenance does a bite check that it can be a ram air door actuator problem. This would be MEL 21-04 that requires a weight penalty correction.

Original NASA ASRS Text

Title: B737-800 Captain raises some interesting points about allowing the crew to placard a single pack controller failure prior to takeoff. This pack light on test could also indicate a ram air door actuator failure which has a performance penalty.

Narrative: Departing on an out and back the First Officer tested the Master Caution system and received a PACK light. The PACK light went out on reset. With the information we have this indicates a single pack controller failure. This is crew placardable with MEL 21-20a. Although I do not know how to tell if we use A) primary or B) secondary for the placard. We completed the turn and were to keep the aircraft for our third leg. Maintenance came to the plane to make a balancing entry and performed a bite check. The bite check indicated a pack temperature controller failure which was placarded with 21-20a. My problem now is that although we are given the ability to placard; the systems knowledge from the MEL book is not comprehensive enough to account for the other problems that can be revealed during a bite check. Without being able to diagnose the problem; I do not believe we should be placarding the pack light that resets. I have also learned that when Maintenance does a bite check that it can be a ram air door actuator problem. This would be MEL 21-04 that requires a weight penalty correction.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

Attributes
ACN	854358
Time
Date	200909
Local Time Of Day	0601-1200
Place
Locale Reference	ZZZ.Airport
State Reference	US
Aircraft 1
Make Model Name	B737-800
Operating Under FAR Part	Part 121
Flight Phase	Parked
Flight Plan	IFR
Component
Aircraft Component	Air Conditioning and Pressurization Pack
Person 1
Function	Captain Pilot Not Flying
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Procedural Other / Unknown

B737-800 captain raises some interesting points about allowing the crew to placard a single pack controller failure prior to takeoff. This pack light on test could also indicate a ram air door actuator failure which has a performance penalty.