AD 2015-21-10 Airworthiness Directives; The Boeing Company Airplanes

Models named: 737-600, -700, -700C, -800, -900, -900ER series. Read the applicability below — it usually turns on serial or part numbers too.

This AD applies to all The Boeing Company Model 737-600, -700, -700C, -800, -900, and -900ER series airplanes, certificated in any category.

Comply with this AD within the compliance times specified, unless already done.

Within 30 days after the effective date of this AD, revise the maintenance or inspection program, as applicable, to add airworthiness limitation number 28-AWL-MOV, “Engine Fuel Shutoff Valve (Fuel Spar Valve) Position Indication Operational Check,” by incorporating the information specified in figure 1 to paragraph (g) of this AD into the Airworthiness Limitations Section of the Instructions for Continued Airworthiness. The initial compliance time for accomplishing the actions specified in 28-AWL-MOV is within 10 days after accomplishing the maintenance or inspection program revision required by this paragraph. Figure 1 to Paragraph ( g ) of This AD—Engine Fuel Shutoff Valve (Fuel Spar Valve) Position Indication Operational Check AWL No. Task Interval Applicability Description 28-AWL-MOV ALI DAILY 737-600, -700, -700C, -800, -900, and -900ER series airplanes Engine Fuel Shutoff Valve (Fuel Spar Valve) Position Indication Operational Check.   INTERVAL NOTE: The operational check is not required on days when the airplane is not used in revenue service The check must be done before further flight once the airplane is returned to revenue service APPLICABILITY NOTE: Only applies to airplanes with a fuel spar valve actuator having part number MA20A2027 (S343T003-56) or MA30A1001 (S343T003-66) installed at the engine fuel spar valve positions Concern: The fuel spar valve actuator design can result in airplanes operating with a failed fuel spar valve actuator that is not reported. A latently failed fuel spar valve actuator could prevent fuel shutoff to an engine. In the event of certain engine fires, the potential exists for an engine fire to be uncontrollable. Perform one of the following checks of the engine fuel spar valve position (unless checked by the flightcrew in a manner approved by the principal operations inspector): A. Operational Check during engine shutdown.   1. Do an operational check of the left engine fuel spar valve actuator.   a. As the ENG 1 START LEVER on the CONTROL STAND is moved to the CUTOFF position, verify the SPAR VALVE CLOSED indication light on the OVERHEAD PANEL for No.1 Engine changes from OFF to BRIGHT then DIM.   b. If the test fails (bright light fails to illuminate), before further flight, repair faults as required (refer to Boeing Aircraft Maintenance Manual (AMM) 28-22-11).   2. Do an operational check of the right engine fuel spar valve actuator.   a. As the ENG 2 START LEVER on the CONTROL STAND is moved to the CUTOFF position, verify the SPAR VALVE CLOSED indication light on the OVERHEAD PANEL for No. 2 Engine changes from OFF to BRIGHT then DIM.   b. If the test fails (bright light fails to illuminate), before further flight, repair faults as required (refer to Boeing AMM 28-22-11).   B. Operational check during engine start.   1. Do an operational check of the left engine fuel spar valve actuator.   a. As the ENG 1 START LEVER on the CONTROL STAND is moved to the IDLE position, verify the SPAR VALVE CLOSED indication light on the OVERHEAD PANEL for No. 1 Engine changes from DIM to BRIGHT then OFF.   b. If the test fails (bright light fails to illuminate), before further flight, repair faults as required (refer to Boeing AMM 28-22-11).   2. Do an operational check of the right engine fuel spar valve actuator.   a. As the ENG 2 START LEVER on the CONTROL STAND is moved to the IDLE position, verify the SPAR VALVE CLOSED indication light on the OVERHEAD PANEL for No. 2 Engine changes from DIM to BRIGHT then OFF.   b. If the test fails (bright light fails to illuminate), before further flight, repair faults as required (refer to Boeing AMM 28-22-11).   C. Operational check without engine operation.   1. Supply electrical power to airplane using standard practices.   2. Make sure No. 1 and No. 2 Engine FIRE switches on the Aft Electronic Panel are in the NORMAL (IN) position.   3. Make sure No. 1 and No. 2 Engine Start Switches on the Forward Overhead Panel are in the OFF or AUTO position.   4. Do an operational check to the left engine fuel spar valve actuator.   a. Move ENG 1 START LEVER on the CONTROL STAND to the IDLE position and wait approximately 10 seconds.   NOTE: It is normal under this test condition for the ENG VALVE CLOSED indication light on the OVERHEAD PANEL to transition from DIM to BRIGHT and stay BRIGHT.   b. Move ENG 1 START LEVER on the CONTROL STAND to the CUTOFF position.   c. Verify the SPAR VALVE CLOSED indication light on the OVERHEAD PANEL for No. 1 Engine changes from OFF to BRIGHT then DIM.   d. If the test fails (bright light fails to illuminate), before further flight, repair faults as required (refer to Boeing AMM 28-22-11).   5. Do an operational check of the right engine fuel spar valve actuator.   a. Move ENG 2 START LEVER on the CONTROL STAND to the IDLE position and wait approximately 10 seconds.   NOTE: It is normal under this test condition for the ENG VALVE CLOSED indication light on the OVERHEAD PANEL to transition from DIM to BRIGHT and stay BRIGHT.   b. Move ENG 2 START LEVER on the CONTROL STAND to the CUTOFF position.   c. Verify the SPAR VALVE CLOSED indication light on the OVERHEAD PANEL for No.2 Engine changes from OFF to BRIGHT then DIM.   d. If the test fails (bright light fails to illuminate), before further flight, repair faults as required (refer to Boeing AMM 28-22-11).   D. Perform an inspection of the engine fuel spar valve actuator position.   NOTE: This inspection may be used whenever the SPAR VALVE light does not function properly.   1. Make sure the ENG 1 START LEVER on the CONTROL STAND is in the CUTOFF position.   NOTE: It is not necessary to cycle the START LEVER to do this inspection.   2. Inspect the left engine fuel spar valve actuator located in the left front spar.   NOTE: The left engine fuel spar valve actuator is on the left wing front spar outboard of the engine strut. Access is through access panel 521BB on the left wing leading edge.   a. Verify the manual override handle on the engine fuel spar valve actuator is in the CLOSED position.   b. Repair or replace any engine fuel spar valve actuator that is not in the CLOSED position (refer to Boeing AMM 28-22-11).   3. Make sure the ENG 2 START LEVER on the CONTROL STAND is in the CUTOFF position.   NOTE: It is not necessary to cycle the START LEVER to do this inspection.   4. Inspect the right engine fuel spar valve actuator located in the right front spar.   NOTE: The right engine fuel spar valve actuator is on the right wing front spar outboard of the engine strut. Access is through access panel 621BB on the right wing leading edge.   a. Verify the manual override handle on the engine fuel spar valve actuator is in the CLOSED position.   b. Repair or replace any engine fuel spar valve actuator that is not in the CLOSED position (refer to Boeing AMM 28-22-11).

This AD was prompted by reports of latently failed fuel shutoff valves discovered during fuel filter replacement. We are issuing this AD to detect and correct latent failures of the fuel shutoff valve to the engine, which could result in the inability to shut off fuel to the engine and, in case of certain engine fires, an uncontrollable fire that could lead to wing failure.

This AD replaces AD 2015-19-03, Amendment 39-18266 (80 FR 55527, September 16, 2015).