by Captain Pat BOONE

Pictures from Jan PASHIDIS Renato ZACHELLO Krister EDLUNDand Chris BRADY author of www.b737.org.uk

Version 2.1 - Jan 20th, 2010The Boeing 737 Exterior Inspection

The Boeing 737 Exterior InspectionSlide * Reference : Boeing 737 FCOM December 2009 Legend : (CL) = Classic (NG) = Next GenerationThis presentation covers the Boeing 737 (Classic & Next Generation) pre-flight Exterior Inspectionaccording the Boeing FCOM Normal Proceduresand Cold Weather Supplementary Procedures.For training only, do not use for operation !Always use your company publications as sole official source !

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The Boeing 737 Exterior InspectionSlide *This 40 slides presentation comes with over 100 pictures and lots of extra information.Whether you are a newbie to the 737or an experienced Boeing 737 captain,you will certainly discover interesting itemsDont run through this presentationclick-click-click-click-click-click Instead, prior to viewing the next page,challenge yourself what am I looking for when Im doing the exterior inspection myself ?and find-out that you may be overlooking some important safety items !

The Boeing 737 Exterior InspectionSlide *This presentation is dividedinto 4 chapters :1- General Guidelines2- The Walk Around3- Cold Weather Operations4- Top 10 Blunders

General guidelines

Surfaces and structures must be clear, not damaged and not missing- Fluids should not be leaking Tires should not be worn, not damaged and no loose treads- Gear struts should not be fully compressed- Engines inlet and tailpipe should be clear, access panels should be secured, the engine exterior should not be damaged and the reverser must be stowed

General GuidelinesThe Boeing 737 Exterior Inspection General guidelines

- Doors and access panels (that are not in use for servicing) should be latched- Probes, vents and static ports must be clear and not damaged- Antennas may not be damaged Light lenses should be clean and not damaged General GuidelinesThe Boeing 737 Exterior Inspection General guidelines

The Walk-aroundExterior Inspection Normal Procedures

Left Forward FuselageThe Boeing 737 Exterior Inspection The Walk-Around Left Forward FuselageProbes, sensors, ports, vents and drains .. CheckDoors and Access Panels (not in use) Latched Exterior InspectionAspirated and non-aspirated temperature probe..Exterior Emergency Exit Lights Additional InformationThe exterior emergency lights illuminate simultaneously with the interior emergency exit lights.Exterior emergency lights are installed next to each entry/service door, overwing exits and behind the wing root (picture).Now, what are you looking for at this location ?

(we need 2 items here)Especially on (CL) make sure the pitot tubes and alpha vane are not damaged by the passenger bridge.On (NG) these probes are moved forward.An aspirated TAT probe delivers an accurate temperature measurement on ground. This probe is cooled by APU bleed air from the left pneumatic duct.An unaspirated TAT probe (recognizable by its perforation and a large hole at the rear of the strut) indicates a valid OAT on ground only when probe heat is OFF and after sufficient cooling time.

NoseThe Boeing 737 Exterior Inspection The Walk-Around NoseRadome .. CheckForward E&E Door .... Secured Exterior InspectionNoise vortex Generators .. Additional InformationThe radome is made of composite material for operation of the WX radar. Six diverter strips transmit static build-up during normal flight. These strips also decrease energy and prevent damage to the ILS and WX antenna (located inside the radome) in the event of a lightning strike. As from January 2005, Noise Vortex Generators are installed on (NG) to reduce the flight deck ambient noise level by 3 decibel.Lightning impact on the nose may puncture or exceptionally destroy the radome.After each lightning strike or bird strike, the radome requires maintenance inspection. Even with no apparent damage on the outside, the composite material may still be damaged (delaminated) on the inside !

What are you looking for at this location ?

(2 items)There are two E&E access doors. This pictures shows the forward E&E door. The forward door provides access to the WX radar and PSEU (NG).

The forward E&E door and the main E&E door (located aft of the nose wheel well) are guarded by a single EQUIP amber light on the flight deck.

Nose Wheel WellThe Boeing 737 Exterior Inspection The Walk-Around Nose Wheel WellTires and wheels ... CheckGear strut and Doors CheckExterior Light .. CheckNose Wheel Steering Assembly . CheckNose Gear Steering Lockout Pin . As neededGear Pin .. As needed Nose Wheel Spin Brake (snubbers) ........ In place Exterior InspectionNose Wheel Well Inspection Flood Light........... Check(CL) Nose Wheel Down & Locked marking....... CheckNose Wheel Steering cable assembly Check Additional InformationAs a general rule, 3 fingers (that is 5 cm or 2 inches) of polished portion of the strut should be visible. Some 737-800 are sensitive to tail-tipping. You may notice up to 2 hands during off-loading.Nose wheel Shimmy DampersNose Wheel Ground Crew HornThis is not the Inspection Flood light, but the Dome Light.

(CL) The Inspection Flood light (on the aft wall) is a NOGO requirement for night flight !The red line indicates the maximum tow bar angle (for tow truck drivers)Picture (NG)Picture (CL) showing both the Nose Gear Steering Lockout Pin (lower left) and the Gear Pin (top)What are you looking for inside and around the nose wheel well ?

(7 items)

Right Forward FuselageThe Boeing 737 Exterior Inspection The Walk-Around Right Forward FuselageProbes, sensors, ports, vents and drains .. CheckDoors and Access Panels (not in use) Latched Oxygen Pressure Relief Green Disc .... In place Exterior InspectionE&E Access Door ...ClosedE&E Outflow Valve ..Check Airflow Additional Information(CL only) Forward Toilet Service Door The Main BatteryThe Light Switch is located hereThe Crew Oxygen Bottle

Although located in the E&E, servicing and removal are done via the forward cargo compartment.The GND SERVICE Bus must be powered for the EQUIP Cooling Normal Exhaust fan to operateWhat are you looking for at this location ?

(3 items)Lets take a look inside the E&E (NG) These avionics may not be touched without carrying the ground wired hand glove, which you find stored near the E&E entry door !The APU starter converter unitand P91 resetCircuit BreakerVerify that the F/O Window Escape Handle is flush.Dont call maintenance for a missing screw or bolt This tiny hole is the outlet for the water drain flexible tube on the flight deck, you know, that annoying tube on (CL) when you close the sliding windowA diverter strip above each Service/Entry Door guides away rain drops rolling down from the fuselage.

Right Wing Root, Pack and Lower FuselageThe Boeing 737 Exterior Inspection The Walk-Around Right Wing Root, Pack and Lower FuselageRam Air Deflector Door .. ExtendedPack and Pneumatic Access Doors ... SecuredProbes, sensors, ports, vents and drains .. CheckExterior Lights CheckLeading Edge Flaps . Check Exterior InspectionAntennas CheckCargo Hold Lighting..Check Lens(NG) Cargo Hold Access Panel(CL) Auxiliary Fuel Tank Vent.. Additional InformationGround Pneumatic Connection (into right Pneumatic Manifold Duct). This connection is located on the right-hand side of the airplane because the ground engineer is headset-connected on the same side.Ground Pre-conditioned Air Connection (Pack) (into the Main Distribution Manifold). The connection is located on the left-hand side of the airplane, since the airports air-conditioning system is integrated into the jetway.Make also sure the inlet is free of FOD, including clothing stowed away by ground personnel on a hot summer day.(NG) Retractable Landing LightWith hydraulic system B unpressurized, the LE Krueger flaps may droop. Never grasp a LE Flap with your hands, because the flaps slam upwards if your fellow pilot on the flight deck pressurizes system B !Make sure there is no protective cover on the static ports. Protective covers are installed for several reasons, including maintenance, painting, washing or to protect the inlet against insects during a stopover.The ATC 2 antennaThese 4 flat antennas are the Radio Altimeter 1 and 2 Transmitter and ReceiverAntenna VHF (CL) COMM 2 (NG) COMM 3A missing or cracked lens cover must be replaced or the light bulb must be removed, as shown here. (MEL 33.04)However, the light in the forward and aft cargo door openings come without a lens cover.The Cargo Compartment Access Panel allows you to enter the forward cargo compartment from the passenger cabin. This panel is located on the right hand side of the passenger cabin near the 10th (737-6/700) 13th (737-8/900) window cutout row E, below the floor carpet.

Do not enter the cargo compartment in case of a (spurious) smoke/fire warning. The panel is installed for the event that luggage is blocking the cargo door handle.(400) Auxiliary Fuel Tank Vent InletWhat are you looking for along this side ?

(5 items)Detail of the Ground Pneumatic Connection (Pack) on the left-hand sideBefore closing-up the cargo compartment, make sure you dont forget about him

The Boeing 737 Exterior Inspection The Walk-Around Airconditioning Bay While we are here, lets take a brief look inside the airconditioning bay. The airconditioning bays are located on each side of the wing roots, forward of the main wheel well. Airconditioning BayThe right pack heat exchangers.The right pack heat exchangers.The air-cycle machineAir conditioning OutletThe Water SeparatorRam Air InletsOutlets

The Boeing 737 Exterior Inspection The Walk-Around Number 2 EngineAccess Panels LatchedProbes, sensors, ports, vents and drains .. CheckFan Blades, Probes and Spinner CheckThrust Reverser ... StowedExhaust area and Tailcone .. Check Exterior InspectionGenerator Drive Oil systemOil leakage....Check within limit Additional InformationNumber 2 EngineT12 Total Inlet Temperature SensorYou dont need to call maintenance for missing bolts. These holes are used to detach the nose cone.You will notice the top of a red locking pin here if the reverser is dispatched inoperative (locked).A view into the engine from the rear with the reverser deployed (open).The oil level indication has a different scale for the left and right engine because of the wing dihedralIf you notice an engine oil leakage during the pre-flight exterior inspection, call maintenance.The maximum allowed number of drops per minute differs by engine type and by engine section.Caution for hot surfaces after recent flightWhat are you looking for at this location ?

(5 items)A small puddle of oil in the engine exhaust plug is acceptable. A large puddle may cause heavy smoke and exceptionally a tail pipe fire up to 10 minutes after engine shutdown.Alignment of these black indicator strips indicate proper stowage of the left and right thrust reverser sleeve.If you focus on this framefor 5 seconds, the engine fan starts to rotate

The Boeing 737 Exterior Inspection The Walk-Around Right Wing and Leading Edge Exterior InspectionWing Anti-Ice Exhaust . Additional InformationRight Wing and Leading EdgeAccess Panels LatchedLeading Edges Flaps and Slats . CheckFuel Measuring Sticks .. Flush and secureWing Surfaces .. CheckFuel Tank Vent . Check(NG) Do you recall the Cold soaked Fuel Frost Limits ? Lower Wing : Upper Wing :The defueling bay door cannot be closed if the defueling valve is open. This valve is manually operated by a handle (shown here).Dont call maintenance to report holes in the leading edge ! These holes serve as wing anti-icing air outlet !Defined cold-soaked fuel frost area painting (NG)Picture of cold soaked fuel frost on lower wing surface. This picture is taken after descent in VMC and landing at an airfield with ambient temperature above 35 C / 95 F !! Also notice there is no ice on the flaps ! Wing anti-icing air supply ductLE slats actuator Max. 3 mm or 1/8 inch Only on the wing itself, not on the flight controls, LE/TE Flaps/Slats and not on winglets. Max. 1,5 mm or 1/16 inch OAT > 0C or 32F No visible moisture Only within the painted area Similar on both wings (!)What are you looking for along the leading edge of the right wing ?

(5 items)Check that Flame Arrestor Pressure Valve Poppet is flush with the wing lower skin. If the valve is popped wing inwards, it must be reset by maintenance.

The Boeing 737 Exterior Inspection The Walk-Around Right Wing Tip and Trailing Edge Exterior InspectionFlight and Ground Spoilers Additional InformationRight Wing Tip and Trailing EdgePosition and Strobe Lights ... CheckStatic Discharge Wicks . CheckAileron and TE Flaps . CheckMEL 33-11 is rather complicated due to different plastic lenses (single or dual) and winglets installed or not.As a general rule at least one red and one green navigation light must operate for night flight.This picture shows a 737-800 with a dual plastic lens and blended winglets.Any idea about the number of static dischargers installed on each wing ? Main Wing : Main Wing (with blended winglets) : Horizontal Stabilizer : Vertical Stabilizer : 4 2 3 4Picture (NG) : The deflection of the flight spoilers deploy is less than the ground spoilers.On NG with the SFP (Short Field Performance) option installed, the deflection angle is further increased.What are you looking for at this location ?

(3 items)

The Boeing 737 Exterior Inspection The Walk-Around Right Main Gear Exterior InspectionBrake Temperature. Additional InformationRight Main GearTires, Brakes and Wheels ... CheckGear Strut, Actuators and Doors CheckGear Pin .. As needed Hydraulic Lines . Secure

Refer to your company manuals and procedures for tire wear limitsor call maintenance.Parking brakes must set in order to check the brake wear indicator pins. With one or both brake pins flush, the brakes can still handle one rejected takeoff.

According to the Maintenance Manual AMM 32-41 you may not leave with a flush pin. Check your company SOP.If one brake wear indicator pin is missing, the brake can stay in service if operation of the remaining pin is satisfactory.If a pin is broken, just consider it missingWhat are you looking for at the right main landing gear ?

(4 items)The aircraft can be dispatched with one, two or all three main landing gear doors missing. Refer to the DDG-CDL for fuel penalties and maintenance actions.As a general rule, the strut should be extended by 3 fingers with passengers and fuel loaded.(NG option) Brake Temp display on the MFD

The Boeing 737 Exterior Inspection The Walk-Around Right Main Wheel Well Exterior InspectionRight Main Wheel WellAPU Fire Control Handle .... Up(NG as installed) NGS light ... CheckWheel Well .. Check The FCOM does not specify what to check, so here are some suggestions :- General condition (no loose cables, no fluid leaks)- Hydraulic System Quantity, Pressure and Filters- Landing Gear Up-Lock system- (CL) Landing Gear Viewing System- (NG) Loose Thread Frangible Fitting

What are you looking for in the Right Main Wheel Well ?

(6 items)Verify that both the Fire Handle and the Bottle Discharge Switch are safety wired.Verify that the operability green indicator light is illuminated, unless the NGS is dispatched inoperative.When the hydraulic fluid return filter is clogged, a red differential pressure indicator will appear on top of the filter (if OAT is above 2 C 36 F).If you notice the red indicator, call maintenanceThe MLG uplock mechanism uses over-center locking to keep the main landing gear up and locked. Two springs hold the uplock hook in the up and locked position.

It has happened that a spring disappeared in flight (if you found it in your garden, please return to company)(NG) If the fitting is broken, the associated landing gear cannot be raised after takeoff.

This may look like a hydraulic fluid leak

However, what you see here is an anti-corrosive protection compoundAnyway, if there is any doubt, call maintenance.The flight can be dispatched with both main wheel well (dome) lights inoperativeHowever, on (CL) an inoperative inspection flood light is a NOGO for night flight ! (two installed one for each gear)

The Boeing 737 Exterior Inspection The Walk-Around Right Main Wheel Well Additional Information A short guided tour inside the Main Wheel Well :Inside the Main Wheel WellThe Spoiler Mixer, mounted on the forward wall.(NG) This is the center tank boost pump. You can find six of these mounted in the forward wall.The F/O Flight Control spoiler quadrant, through cables connected with the F/O flight deck control wheelThe CAPT Flight Control aileron quadrant, through cables connected with the Captains flight deck control wheelHydraulic system B Pressure ModuleHydraulic system B reservoir pneumatic air pressure indicatorThe TE Flaps hydraulic motor and the alternate electric motor are integrated in the same housing on the aft wall of the wheel well. Both motors drive the TE flaps through common orange/black painted shafts.The accumulator brake pressure indicatorThe Standby hydraulic system reservoir is located on the center keel beam.This picture is (NG).Mounted on the forward part of the keel beam, this is the PTU.This is the system B EMDP (Electric Motor Driven Pump).The system B EDP (Engine Driven Pump) is located in Engine 2 of course.This is the Thrust Reverser Control Valve for Engine 2. This is the system A EMDP (Electric Motor Driven Pump).The handle on the forward side should be wired and pointing upwards. The handle is for maintenance only. If the handle is rotated, the engine reverser is de-activated(NG) TE Flap Transmission : this unit transmits power from the orange/black torque shaft to the TE flaps for that side. So, there are two of these beasts installed in the wheel well.There is a relatively large empty space next to and aft of each flap transmission. It can even hide a stowaway. Always worth a double check

The Boeing 737 Exterior Inspection The Walk-Around Right Aft Fuselage Exterior InspectionToilet Waste System..VHF Comm Antenna.. Additional InformationRight Aft FuselageDoors and Access Panels . LatchedNegative Pressure Relief Door .. ClosedOutflow Valve . CheckProbes, sensors, ports, vents and drains .. CheckAPU Air Inlet Open(CL) APU Fire Bottle ..... Check

What are you looking for along the aft fuselage ?

(6 items - NG) (7 items CL)The water service panel is located on the right side (NG) left side (CL) of the airplane. This picture is (NG).The toilet service panel is located on the opposite side, with an extra toilet access panel in the front (CL).On recent delivered (NG) the main outflow valve comes with teeth to reduce aerodynamic noise. (NG) Aft Cargo Compartment

Behind this bulkhead is the toilet waste tank and the compressor.Antenna VHF (CL) COMM 3 (NG) COMM 2(CL) Verify that the Squib Discharge disc (yellow) and the Bottle Overpressure disc (red) are in placeVerify the cargo compartment entry for any dents

The Boeing 737 Exterior Inspection The Walk-Around Tail Exterior InspectionTailVertical Stabilizer and Rudder .... CheckHorizontal Stabilizer and Elevator .. CheckElevator Feel Probes Check(400-800-900) Tail Skid ... CheckStatic Discharge Wicks .... CheckStrobe Light CheckAPU Cooling Air Inlet and Exhaust Outlet . Check

What are you looking for around the tail ?

(8 items)APU Cooling Air InletAPU Exhaust Outlet

The Boeing 737 Exterior Inspection The Walk-Around Tail Additional InformationLogo LightHorizontal Stabilizer-to-Body Sliding SealsAntenna HF and VOR

TailLocation of the VOR/LOC antennaLocation of the HF antenna(NG) The logo light is powered from Main Bus 1. Hence the logo lights do not illuminate with the CAB/UTIL switch in OFF!If the upper or lower seal is missing, call maintenance. When dispatched with the seal removed, apply the performance weight penalties from the DDG / CDL.Now, lets take a look, where you have never been before, inside the tail cone :Stabilizer Trim system ..APU Inlet Door system .APU Fire Extinguisher system .Other

The famous Stab trim jackscrewThe Stab trim control cable drum. The cables are connected to the flight deck manual trim wheels.The electric Stab trim actuatorThe APU inlet door as seen from the inside. This here is the electric door actuator.The rudder steering cables, connected to the flight deck rudder pedals.The aft pressure bulkhead is hemispheric on 737-100 thru 800 and flat on the 900

The Boeing 737 Exterior Inspection The Walk-Around Left side Differences with Right SideLeft sideLeft Aft Fuselage : (NG) Waste Compressor Vent . Check

Left Main Wheel Well : Fire Discharge Bottles .... CheckWhat additional items will you be checking on the left side of the airplane ?

(2 items - NG) (1 item CL)During the exterior inspection you may notice the sound of the vacuum compressor when the cabin crew flushes the toilets.A malfunctioning air/waste separator may direct waste to the air outlet i.s.o. towards the waste tank

So here is a good advice :stay away from this hole !As a general rule both pressure indicators should point upwards. They may tend slightly to the left on cold days and slightly to the right on hot days as pressure inside the bottles changes with OAT. Additional InformationEntry / Service Door Floor Drains . Check

When you return to the flight deck, take a look at these drains. Very often, the drains are clogged ! These drains guide away rain water that has entered the cabin through the associated door. A clogged drain may cause rain water to seep into the E&E, causing damage to electronics.

Cold Weather OperationsExterior Inspection Supplementary Procedures

The Boeing 737 Exterior Inspection Cold Weather Operations Pay extra attention to the following items :Surfaces CheckControl Balance Cavities CheckPitot Probes and Static ports . CheckAir Conditioning Inlets and Exits CheckEngine Inlets . CheckFuel Tank Vents ... CheckLanding Gear Doors .... CheckAPU Air Inlets ... Check

The Boeing 737 Exterior Inspection Cold Weather OperationsIce formation in the engine inletClear ice on the leading edgeIce formation on the pitot tubes Some Pictures :Ice formation on the engine fan after a short taxi time

Top 10 Blunders !In fact, we can as well start with this classic one : Tools or an oil can accidentally left behind in the main wheel well by maintenance personnel.

Number 10General condition OK ?How about these 3 tools?The Boeing 737 Exterior Inspection Top 10 Blunders

Number 9A large dent in the fuselage may easily go unnoticedThe Boeing 737 Exterior Inspection Top 10 Blunders

Number 8Dont tell me I didnt warn you !The Boeing 737 Exterior Inspection Top 10 Blunders

Number 7(NG) The main gear frangible fitting may never be used to attach the fuel truck ground wiring cable !OK, whats wrong here ?The Boeing 737 Exterior Inspection Top 10 Blunders

Number 6The Boeing 737 Exterior Inspection Top 10 BlundersThere is no potential danger that the door opens in flight when the Z-Handle is not correctly stowed. However, you will probably experience additional ambient noise in flight

Number 5OK, whats wrong here ?This rod is broken, so you will be flying with the right nose wheel well door openThe Boeing 737 Exterior Inspection Top 10 Blunders

Number 4During the walk-around in heavy rain, you may perhaps not be looking upwards and these missing access panels from the Horizontal Stabilizer may go unnoticed

Furthermore, always pay extra attention to access panels when the airplane is being returned from maintenance.The Boeing 737 Exterior Inspection Top 10 Blunders

Number 3(CL) While the gear pin may have drawn your attention, you should also have noticed that the red painting is missing and/or covered with lubricating oil This is a NOGO !Anything wrong here ?The Boeing 737 Exterior Inspection Top 10 Blunders

Number 2This engine looks in good shape ?You caught a bird into the N2 compressor during landing.This may go unnoticed, especially during a night time walk-around without carrying a flash-light The Boeing 737 Exterior Inspection Top 10 Blunders

Number 1And our Number 1 winner today is ???

The (smaller) main wheel of a Boeing 737-500 mounted on the Boeing 737-400So, always take a look to the wheels !

The Boeing 737 Exterior Inspection Top 10 Blunders

the end - for more information www.B737MRG.net www.B737.org.uk The Boeing 737 Exterior InspectionSlide *Have a safe flight !