SBU Merpati Maintenance Facility Approved Maintenance Organization Doc. No: AP.2 - 011 WORK INSTRUCTION 1-3 AIRCRAFT TOWING 1.SCOPE Work Instruction is a procedure used to perform on B737 200,300,400,500 types of aircraft towing at SBU Merpati Maintenance Facility. 2.PURPOSE To confirm the normal procedure to perform aircraft towing as stated in the Aircraft Maintenance Manual. 3.DEFINITION 3.1 3.2 Aircraft Towing is the process of towing the aircraft to the parking lot that has been determined. Tow bar is a device used to connect the aircraft with a tractor puller. 4. REFERENCE 4.1. 4.2. Aircraft Maintenance Manual ATA 9. Maintenance Organization Exposition (MOE) 5. GENERAL 5.1. 5.2. The airplane is normally towed or pushed by a tow bar attached to the nose gear. Maximum normal towing turning limits are indicated by painted stripes on the nose gear doors. Towing airplane with either or both engines removed presents no problem as long as the center of gravity remains forward of the aft center of gravity limits. 6. PREPARE FOR TOWING AIRPLANE 6.1. A. Check airplane is within center of gravity towing limitations and for fuel imbalance. 6.2. Check that all landing gear ground lock pins are installed . 6.3. Tires and shock struts properly inflated . 6.4. Apply external electrical power or start and operate APU . With external power applied or APU providing electrical power, parking brakes in parked position, and hydraulic system ground interconnect valve on (open), system B pump will pressurize both inboard and outboard brake accumulators A and B. If parking brakes Revision: 0 September 29, 2011 SBU Merpati Maintenance Facility Approved Maintenance Organization Doc. No: AP.2 - 011 WORK INSTRUCTION 2-3 AIRCRAFT TOWING 6.5. 6.6. 6.7. 6.8. 6.9. 6.10. 6.11. 6.12. 6.13. 6.14. are off, only outboard brake accumulator B will be charged and outboard brakes continuously pressurized. Check that brake hydraulic pressure is normal, approximately 3000 psi. Check that antiskid switch is off. On airplanes without nose gear steering depressurization valve or if Lockout Pin is not installed. 1. Check that hydraulic system A is depressurized. 2. Remove external electrical power . The APU may be operated if the engines are not operating, or the engines are operating but no electrical power changes are made while towing. On airplanes with nose gear steering depressurization valve, depress button and install nose gear steering lockout pin in steering depressurization valve . Connect interphone system between control cabin, tow tractor operator and towing ground crew. Check that ramp area is cleared of all stands and equipment in the towing path. Connect tow bar to tow tractor and to airplane. Remove airplane static ground wires. Close the fan cowl panels, thrust reverser . To tow the airplane with the entry or lower cargo door open is optional. 7. PROCEDURE 7.1. Position wing, tail, tow tractor operator and ground crew so that all are in visual contact. 7.2. Check that cockpit man, ground crew, and tow tractor operator are in intercom communication. 7.3. Check that wheel chocks are removed. 7.4. Check that hydraulic brakes are released. 7.5. Tow airplane. Begin towing slowly and straight ahead before attempting to turn. 7.6. Limit brake applications to minimum use within safety limitations. Fully charged accumulators are capable of approximately three brake applications. 7.7. Maximum normal turning angle is 78 degrees as indicated by red stripes on nose gear doors. Revision: 0 September 29, 2011 SBU Merpati Maintenance Facility Approved Maintenance Organization Doc. No: AP.2 - 011 WORK INSTRUCTION 3-3 AIRCRAFT TOWING 7.8. 7.9. Finish towing in a straight path for a minimum of 10 feet to relieve turning stresses remaining in tires and shock struts. At end of towing, position wheel chocks fore and aft of a main gear wheel on each main gear. Set parking brakes if required. Disconnect tow bar. On those airplanes equipped with a nose gear steering depressurizing valve, remove nose gear steering lockout pin from depressurization valve. Revision: 0 September 29, 2011
