B727 crew found both channels of the autoplt were malfunctioning.

Attributes
ACN	470810
Time
Date	200004
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : orl.vortac
State Reference	FL
Altitude	msl bound lower : 1000 msl bound upper : 20000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : mco.tracon
Operator	common carrier : air carrier
Make Model Name	B727-200
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	climbout : vacating altitude
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 100 flight time total : 5000 flight time type : 1900
ASRS Report	470810
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : instrument pilot : commercial
Events
Anomaly	aircraft equipment problem : less severe maintenance problem : improper maintenance non adherence : published procedure non adherence : company policies other anomaly other
Independent Detector	other flight crewa other flight crewb
Resolutory Action	none taken : detected after the fact
Consequence	other
Factors
Maintenance	contributing factor : schedule pressure performance deficiency : fault isolation performance deficiency : inspection performance deficiency : repair
Supplementary
Problem Areas	Maintenance Human Performance Company Aircraft
Primary Problem	Maintenance Human Performance

Narrative:

On apr/wed/00, I was captain on air carrier flight abc from sfb to gyy that departed approximately XA00. I received the aircraft from the inbound crew with the 'B' channel of the autoplt written up as inoperative and placed on a deferred maintenance status due to a trim and porpoising problem. This left the 'a' channel available for my use. Climbing through 10000 ft, I engaged the autoplt in the 'a' channel and noticed very quickly that the autoplt was not trimming the airplane as it should. When the autoplt was selected to altitude hold mode, the yoke began traveling forward, followed by opposite direction trimming. I disengaged the autoplt, manually trimmed the airplane and once again engaged the autoplt. The result was the same as before. I started thinking that this is exactly what the logbook said the 'B' channel was doing and that maybe they got the 'a' and 'B' channel mixed up in the deferral, so I tried the 'B' channel with exactly the same results as the 'a' channel. I contacted dispatch and they recommended continuing to gyy, adding that they would have maintenance meet the airplane. After landing in gyy, I made an entry in the maintenance logbook and described the autoplt discrepancy as I have just stated. In retrospect, I should not have tried the 'B' channel of the autoplt as it was on a deferred maintenance status.

Original NASA ASRS Text

Title: B727 CREW FOUND BOTH CHANNELS OF THE AUTOPLT WERE MALFUNCTIONING.

Narrative: ON APR/WED/00, I WAS CAPT ON ACR FLT ABC FROM SFB TO GYY THAT DEPARTED APPROX XA00. I RECEIVED THE ACFT FROM THE INBOUND CREW WITH THE 'B' CHANNEL OF THE AUTOPLT WRITTEN UP AS INOP AND PLACED ON A DEFERRED MAINT STATUS DUE TO A TRIM AND PORPOISING PROB. THIS LEFT THE 'A' CHANNEL AVAILABLE FOR MY USE. CLBING THROUGH 10000 FT, I ENGAGED THE AUTOPLT IN THE 'A' CHANNEL AND NOTICED VERY QUICKLY THAT THE AUTOPLT WAS NOT TRIMMING THE AIRPLANE AS IT SHOULD. WHEN THE AUTOPLT WAS SELECTED TO ALT HOLD MODE, THE YOKE BEGAN TRAVELING FORWARD, FOLLOWED BY OPPOSITE DIRECTION TRIMMING. I DISENGAGED THE AUTOPLT, MANUALLY TRIMMED THE AIRPLANE AND ONCE AGAIN ENGAGED THE AUTOPLT. THE RESULT WAS THE SAME AS BEFORE. I STARTED THINKING THAT THIS IS EXACTLY WHAT THE LOGBOOK SAID THE 'B' CHANNEL WAS DOING AND THAT MAYBE THEY GOT THE 'A' AND 'B' CHANNEL MIXED UP IN THE DEFERRAL, SO I TRIED THE 'B' CHANNEL WITH EXACTLY THE SAME RESULTS AS THE 'A' CHANNEL. I CONTACTED DISPATCH AND THEY RECOMMENDED CONTINUING TO GYY, ADDING THAT THEY WOULD HAVE MAINT MEET THE AIRPLANE. AFTER LNDG IN GYY, I MADE AN ENTRY IN THE MAINT LOGBOOK AND DESCRIBED THE AUTOPLT DISCREPANCY AS I HAVE JUST STATED. IN RETROSPECT, I SHOULD NOT HAVE TRIED THE 'B' CHANNEL OF THE AUTOPLT AS IT WAS ON A DEFERRED MAINT STATUS.

Data retrieved from NASA's ASRS site as of July 2007 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.