B757 captain experiences asymmetric spoiler extension in flight causing the aircraft to roll left. U...

Narrative:

While on the descent; I extended the speed brakes to make a crossing restriction. We were at 27;000 at 320 KTS assigned. The autopilot was on; and as the speed brakes extended; the aircraft used 1 unit of right aileron to fly straight and level. When the speedbrakes were retracted; the ailerons returned to neutral. As there was history of this; I disconnected the autopilot and again extended the speedbrakes. The aircraft rolled quickly to the left; and right aileron was need to stop the roll. We sent a report to maintenance. When we got to the gate; the mechanics who met the airplane said that maintenance was going to defer the auto speed brake function and send the aircraft to las; since they had a long runway. Three major issues with this thinking.1-this is a chronic write up; with each time; ground test; no faults noted; as the response.2-this does not address the write up. Spoilers in flight and on the ground are two completely different issues.3-an aircraft that is headed to las may have a situation arise which requires an immediate landing at nearest suitable airport and the speed brakes may be required due to landing on a shorter runway. The MEL was designed to get an airplane back to a maintenance base to be fixed; not to fly from a maintenance base at the convenience of the router!

Original NASA ASRS Text

Title: B757 Captain experiences asymmetric spoiler extension in flight causing the aircraft to roll left. Upon arrival Maintenance elects to defer the auto speed brake function and send the aircraft out.

Narrative: While on the descent; I extended the speed brakes to make a crossing restriction. We were at 27;000 at 320 KTS assigned. The autopilot was on; and as the speed brakes extended; the aircraft used 1 unit of right aileron to fly straight and level. When the speedbrakes were retracted; the ailerons returned to neutral. As there was history of this; I disconnected the autopilot and again extended the speedbrakes. The aircraft rolled quickly to the left; and right aileron was need to stop the roll. We sent a report to Maintenance. When we got to the gate; the mechanics who met the airplane said that Maintenance was going to defer the auto speed brake function and send the aircraft to LAS; since they had a long runway. Three major issues with this thinking.1-This is a chronic write up; with each time; ground test; no faults noted; as the response.2-This does NOT address the write up. Spoilers in flight and on the ground are two completely different issues.3-An aircraft that is headed to LAS may have a situation arise which requires an immediate landing at nearest suitable airport and the speed brakes may be required due to landing on a shorter runway. The MEL was designed to get an airplane back to a maintenance base to be fixed; not to fly from a maintenance base at the convenience of the router!

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	915269
Time
Date	201010
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.ARTCC
State Reference	US
Aircraft 1
Make Model Name	B757-200
Operating Under FAR Part	Part 121
Flight Phase	Descent
Flight Plan	IFR
Component
Aircraft Component	Speedbrake/Spoiler
Person 1
Function	Pilot Not Flying Captain
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 150 Flight Crew Total 22500 Flight Crew Type 2800
Events
Anomaly	Aircraft Equipment Problem Less Severe

B757 captain experiences asymmetric spoiler extension in flight causing the aircraft to roll left. Upon arrival maintenance elects to defer the auto speed brake function and send the aircraft out.