A B777 autothrottle system malfunctioned as the EICAS alerted autopilot with an audible warning. The...

Narrative:

Good weather; departing on 02R. After takeoff in the initial climb phase; the autopilot began in the LNAV mode to fly the published departure. Selected the autopilot between 500-1;000 ft; did normal flap schedule. During this process the EICAS displayed 'autopilot.' the first officer was in the process of the after takeoff checklist and check in with ATC. We noticed the throttles had gone to the mechanical stops and speed began to exceed 250 KTS. The first officer finally got to check in with the ATC departure and they requested us to slow to 250 KTS; which during this time; I selected speed intervention. The speed bug on the pfd was indicating 250 KTS. The speed window indicated 250 KTS when selected; but could not change the speed bug on the pfd in either direction. Continued to pull power back; but throttles kept going back to mechanical stop. Deselected autopilot; deselected autthrottles on the MCP; but also had to disconnect the autthrottles on the throttles before regaining control. Deselected F/D. Flew the departure manually for a short time and then reselected the F/D's on; autopilot on; autthrottles on and the aircraft seemed to be normal. EICAS advisory 'autopilot' went away. Autopilot automation failed to comply with airspeed. Next time I get an EICAS 'autopilot' advisory I will immediately disconnect all automation.

Original NASA ASRS Text

Title: A B777 autothrottle system malfunctioned as the EICAS alerted AUTOPILOT with an audible warning. The aircraft accelerated beyond 250 KTS toward 300 KTS; which required disconnecting all autothrottle automation to regain control.

Narrative: Good weather; departing on 02R. After takeoff in the initial climb phase; the autopilot began in the LNAV mode to fly the published departure. Selected the autopilot between 500-1;000 FT; did normal flap schedule. During this process the EICAS displayed 'autopilot.' The First Officer was in the process of the after takeoff checklist and check in with ATC. We noticed the throttles had gone to the mechanical stops and speed began to exceed 250 KTS. The First Officer finally got to check in with the ATC departure and they requested us to slow to 250 KTS; which during this time; I selected speed intervention. The speed bug on the PFD was indicating 250 KTS. The speed window indicated 250 KTS when selected; but could not change the speed bug on the PFD in either direction. Continued to pull power back; but throttles kept going back to mechanical stop. Deselected autopilot; deselected autthrottles on the MCP; but also had to disconnect the autthrottles on the throttles before regaining control. Deselected F/D. Flew the departure manually for a short time and then reselected the F/D's on; autopilot on; autthrottles on and the aircraft seemed to be normal. EICAS advisory 'autopilot' went away. Autopilot automation failed to comply with airspeed. Next time I get an EICAS 'autopilot' advisory I will immediately disconnect all automation.

Data retrieved from NASA's ASRS site as of July 2013 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	1112760
Time
Date	201309
Local Time Of Day	0601-1200
Place
Locale Reference	ZZZZ.ARTCC
State Reference	FO
Environment
Flight Conditions	VMC
Aircraft 1
Make Model Name	B777-200
Operating Under FAR Part	Part 121
Flight Phase	Climb
Flight Plan	IFR
Component
Aircraft Component	Autothrottle/Speed Control
Person 1
Function	Pilot Flying Captain
Qualification	Flight Crew Air Transport Pilot (ATP)
Person 2
Function	Pilot Not Flying First Officer
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Procedural Clearance Deviation - Speed All Types

A B777 autothrottle system malfunctioned as the EICAS alerted autopilot with an audible warning. The aircraft accelerated beyond 250 KTS toward 300 KTS; which required disconnecting all autothrottle automation to regain control.