AD/B737/301 Spoiler Actuator Jamming (Cth)

AIRWORTHINESS DIRECTIVE

For the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.001(1) of CASR 1998.  The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.

Boeing 737 Series Aeroplanes

AD/B737/301 Spoiler Actuator Jamming 5/2007 DM

Applicability:	Model 737-800 series aeroplanes, serial numbers 32685, 34277 through 34281 inclusive, 34474, 34475, 34654 through 34656 inclusive, 34690, 34948, 34949, 35091 through 35093 inclusive, 35103, 35134, 35176 through 35183 inclusive, 35330, 35331, 35558, 35559, and 36323 through 36328 inclusive.
Requirement:	1.    Visually check the spoilers to determine spoiler position, in accordance with Boeing 737 Flight Crew Operations Manual Bulletin No. TBC-67, dated 5 March 2007.  If all spoilers are determined to be properly stowed, no further action is necessary in accordance with this Requirement.
The visual checks may be performed by qualified personnel or flightcrew and must be entered into the aircraft records showing compliance with this Directive.
2.    If, during the Requirement 1 visual check, any spoiler is found to be improperly stowed (in the up position with the speedbrake handle in the down position), replace the flight spoiler actuator with a flight spoiler actuator, having part number (P/N) P655A0001-01 or higher dash number, in accordance with a method approved by the Manager, Seattle Aircraft Certification Office (ACO), United States Federal Aviation Administration (FAA).
The "Flight Spoiler Actuator Removal” task and the "Flight Spoiler Actuator Installation” task in Chapter 27-61-51 of the 737/600/700/800/900 Aircraft Maintenance Manual (AMM) are approved methods for the replacement (removal and installation) of the flight spoiler actuator.
3.    Carry out an operational test of the speedbrake control system in accordance with a method approved by the Manager, Seattle ACO.
The "Speedbrake Control System Operational Test” specified in Chapter 27-62-00 of the 737/600/700/800/900 AMM is one approved method for the operational test of the speedbrake control system.
Note 1:  The optional installation of flight spoiler actuator, P/N P655A0001-01 or higher dash number, in all eight flight spoiler positions ends the need for the Requirement 1 repetitive visual checks and the Requirement 3 operational checks.

4.    If, during the Requirement 3 operational test, any spoiler panel is found to be fully extended with the speedbrake handle down, or if any spoiler panel is found fully retracted when the speedbrake handle is up, replace the flight spoiler actuator in accordance with the actions specified in Requirement 2.
5.    The Master Minimum Equipment List Item 27-7, "Auto Speed Brake System,'' is no longer applicable to Model 737-800 series aeroplanes equipped with an Short Field Performance (SFP) package.
6.    Flight spoiler actuators, P/N P655A0001-00, may not be installed on any aeroplane as a replacement spare.
7.    If any spoiler is found to be improperly stowed during any visual check required by this Directive, report the following information electronically to Boeing using the established Boeing Communications System (BCS):
Aeroplane serial number, jam position, spoiler panel number or wing position of the spoiler that jammed, date of visual check, and flight hours accumulated on the aeroplane.
Note 2:  FAA Emergency AD 2007-06-51 refers.
Compliance:	For Requirement 1 - After every landing and after any rejected takeoff manoeuvre after the effective date of this Directive, until installation of flight spoiler actuator, P/N P655A0001-01 or higher dash number, in all eight flight spoiler positions is accomplished.
For Requirement 2 - Before further flight after the Requirement 1 visual check.
For Requirement 3 - After any maintenance action that operates the spoiler system, until the installation of flight spoiler actuator, P/N P655A0001-01 or higher dash number, in all eight flight spoiler positions is accomplished.
For Requirement 4 - Before further flight after the Requirement 3 operational test.
For Requirement 5 and 6 - As of the effective date of this Directive.
For Requirement 7:
a.     For visual checks accomplished before the effective date of this Detective - Within seven days after effective date of this Directive.
b.    For visual checks accomplished after the effective date of this Detective - Within seven days after carrying out the inspection.
This Airworthiness Directive becomes effective on 19 March 2007.

Background:

The FAA has received a report of seven flight spoiler actuator jams on Model 737-800 Short Field Performance (SFP) aeroplanes.  The cause of the failure has been identified as interference within the actuator main control valve.

This Directive is issued to detect and correct any spoiler panel that is found in the up position with the speedbrake handle in the down position, which could result in a spoiler actuator hardover and could cause the spoiler surface to jam in the fully extended position.  Two or more hardover failures of the spoiler surfaces in the up direction on the same wing, if undetected prior to takeoff, can cause significant roll and consequent loss of control of the aeroplane.

Charles Lenarcic
Delegate of the Civil Aviation Safety Authority

14 March 2007