B737mrg exterior inspection

The Boeing 737
Exterior Inspection

by Captain Pat BOONE

Pictures from Jan PASHIDIS – Renato ZACHELLO – Krister EDLUND
and Chris BRADY – author of www.b737.org.uk
Version 2.1 - Jan 20th, 2010

The Boeing 737 Exterior Inspection

This presentation covers
the Boeing 737 (Classic & Next Generation)
pre-flight Exterior Inspection
according the Boeing FCOM Normal Procedures
and Cold Weather Supplementary Procedures.

For training only, do not use for operation !
Always use your company publications
as sole official source !

Reference : Boeing 737 FCOM
December 2009

Legend : (CL) = Classic
(NG) = Next Generation

Slide 2


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Slide 3


This 40 slides presentation comes with
over 100 pictures and lots of extra information.
Whether you are a newbie to the 737
or an experienced Boeing 737 captain,
you will certainly discover interesting items…
Don’t run through this presentation
click-click-click-click-click-click …

Instead, prior to viewing the next page,
challenge yourself “what am I looking for
when I’m doing the exterior inspection myself ?”
and find-out that you may be overlooking
some important safety items !

Slide 4


This presentation is divided
into 4 chapters :

1- General Guidelines
2- The Walk Around
3- Cold Weather Operations
4- Top 10 Blunders…

Slide 5

 General guidelines

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 guidelines

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

The Walk-around
Exterior Inspection – Normal Procedures

 The Walk-Around  Left Forward Fuselage

Left Forward Fuselage 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.
Exterior Inspection

Probes, sensors, ports, vents and drains …….. Check
Doors and Access Panels (not in use) ……… Latched
Especially on (CL) make sure the
pitot tubes and alpha vane are not
Additional Information damaged by the passenger bridge.
On (NG) these probes are moved
forward.
Aspirated and non-aspirated temperature probe……..
Exterior Emergency Exit Lights…………………………

“Now, what are you looking for lights
The exterior emergency
at this location ?” interiorsimultaneously with
illuminate
the emergency exit lights.
An aspirated TAT probe delivers an
Exterior emergency lights are
accurate temperature measurement
installed next to each entry/service
(we need 2 items here) on ground. This probe is cooled by
door, overwing exits and behind
APU bleed air from the left
the wing root (picture).
pneumatic duct.

 The Walk-Around  Nose

Nose

Exterior Inspection

Radome ………………………………………….. Check
Forward E&E Door ………………………...…. Secured

The radome is made of composite material
Additional Information for operation of the WX radar.
Six diverter strips transmit static build-up
during normal flight. the nose mayalso
Lightning impact on These strips puncture
Noise vortex Generators ………………………………..
decrease energydestroy the radome. to the
or exceptionally and prevent damage
There After each lightning strike or bird strike, the
are two E&E access doors. This pictures
ILS and WX antenna (located inside the
showsradome requires maintenance inspection.
the forward E&E door. The forward door
radome) in the event of a lightning strike.
provides access no the WX radar and PSEU (NG).
Even with to apparent damage on the
The forward E&Efrom January 2005,E&E door be
outside, thedoor and the main may still
As
composite material
“What are you looking for
damaged (delaminated) well) are
the nose wheel on the inside !
(located aft of Noise Vortex Generators guarded
are
by a single EQUIP amber (NG)on the flight deck.
installed on light to reduce the
at this location ?” flight deck ambient noise level
by 3 decibel.

(2 items)

 The Walk-Around  Nose Wheel Well

Nose Wheel Well

Exterior Inspection

Tires and wheels ….…………………………….. Check
Gear strut and Doors …………………………… Check
Exterior Light …………………………………….. Check
Nose Wheel Steering Assembly ………………. Check
Nose Gear Steering Lockout Pin …………. As neededInspection Flood
This is not the
Gear Pin …………………………………….. indicates the Dome Light.
The red line As needed
light, but the
maximum tow (CL)angleInspection Flood light
bar The
Nose Wheel Spin Brake (snubbers) ……........ In place is a NOGO
(for tow truck drivers) aft wall)
(on the
Nose wheel
Shimmy Dampersfor night flight !
requirement
As a general rule, “3 fingers” (that is
Additional Information Picture (CL) showing both the Nose Gear Steering
5 cm or 2 inches) of polished portion
Lockout Pin (lower left) and the Gear Pin (top)
of the strut should be visible.
inside and around
Nose Wheel Well Inspection 737-800 are sensitive to Check
Some Flood Light...........
tail-tipping. You may notice up to
the nose wheel well ?”
(CL) Nose Wheel Down “2 hands” during off-loading.
& Locked marking....... Check
Nose Wheel Steering cable assembly ………… Check (NG) Picture
Nose Wheel
(7 items) Ground Crew Horn

 The Walk-Around  Right Forward Fuselage

A diverter strip above each Service/Entry Door guides
away rain drops rolling down from the fuselage.
Right Forward Fuselage

Exterior Inspection

Doors and Access Panels (not in use) ……… The Crew Oxygen Bottle ground touched
Latched avionics may not be wired
These
without carrying the
Oxygen Pressure Relief Green Disc ……...….Although located in which youservicing
Theplaceglove, the E&E, find stored
In APU starter
hand
converter unit E&E entry door !
near the
and removal are done via the forward
cargoP91 reset
and compartment.
Additional Information Circuit Breaker only)
(CL
Forward Toilet Service Door

E&E Access Door ……………………………..….Closed the F/O Window
Verify that
E&E Outflow Valve ………………………..Check AirflowHandle ishere
The Light Switch is located flush.
Escape

Let’s take a look inside the E&E (NG)
“What are you looking for The Main Battery

at this location ?” Don’t call maintenance for a missing
screw or bolt…
ThisThe GND is the outlet for the water
tiny hole SERVICE Bus
drain flexiblepoweredthe flight deck,
must be tube on for the
(3 items) you EQUIP Cooling Normal on (CL)
know, that annoying tube
when you close theoperate…
Exhaust fan to sliding window…

 The Walk-Around  Right Wing Root, Pack and Lower Fuselage

Right Wing Root, Pack and Lower Fuselage
The ATC 2 antenna
Exterior Inspection The Cargo Compartment Access Panel allows However, the light in the forward and aft cargo
you to enter the forward cargo compartment door openings come without a lens cover.
Ram Air Deflectorfrom the passenger cabin. This panel isExtended
Door …………………..… located
A missing or cracked lens cover must be
on the right hand side of the passenger cabin
Pack and Pneumatic the 10th (737-6/700) – ………... Secured must be
near Access Doors 13replaced or the light bulb
th (737-8/900)

window cutout – row E, below removed,carpet.
the floor as shown here. (MEL 33.04)
Do not enter the cargo compartment in case of
Exterior Lights …………………………………… is Connectionthe cargo
a (spurious) smoke/fire warning. The panel Check This connection
Ground Pneumatic
Before closing-up
Pneumatic Manifold Duct).
(into right
compartment, make sure you
installed for the event that luggage is blocking
Leading Edge Flapscargo door handle. is located ondon’tright-hand side of the
the ……………………………. Check him… the
forget about
airplane because the ground engineer isTank Vent Inlet
(400) Auxiliary Fuel
headset-connected on the same side.
Additional Information
With hydraulic system B unpressurized, the
Antenna’s …………………………………………Check
LE Krueger flaps may droop.
Never grasp a LE Flap with your hands,
Cargo Hold Lighting…………………..……Check Lens
because the flaps slam upwards if your fellow
pilot on the sure there is no protective cover !
Make flight deck pressurizes system B
(NG) Cargo Hold Access Panel…………………………
along this side ?” on the static ports.
(CL) Auxiliary Fuel Tank Vent………………………….. inletarefree of FOD,
Protective covers are installed for the
Make also sure
These 4 flat antenna’s
is
several reasons, including maintenance, Landing Light
including clothing stowed away by
(NG) Retractable
(5 items) painting, washing or ground personnel Air 1 and summer day. (into the
Ground the Radiothe inleton a hot 2
to protect Altimeter Connection (Pack)
Pre-conditioned Antenna VHF
against insects duringTransmitter of the Groundconnection is located
a stopover.and Receiver Pneumatic
Main Distribution Manifold). The COMM 2 Connection
Detail (CL)
on the left-hand sideon the (NG) COMM 3 the airport’s
(Pack) of the left-hand since
airplane, side
air-conditioning system is integrated into the jetway.

 The Walk-Around  Airconditioning Bay

Airconditioning Bay
Ram Air Inlets

While we are here, let’s 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.
The air-cycle machine

The Water Separator

The right pack heat
exchangers.

Air conditioning Outlet

Outlets

 The Walk-Around  Number 2 Engine

Number 2 Engine

Exterior Inspection

Access Panels …………………………………notice an engine oil leakage
If you Latched
during the pre-flight exterior
Probes, sensors, ports, vents and drains inspection, call maintenance.
…….. Check
Fan Blades, Probes and Spinner ……………… Check number of
The maximum allowed
drops per minute differs by engine
Thrust Reverser ………………………………... Stowedsection.
type and by engine

Exhaust area and Tailcone …………………….. Check
Alignment of these black indicator
Generator Drive Oil system………………………………
strips indicate proper stowage of to call
You don’t need
the left and right thrust reverser missing bolts.
maintenance for
Oil leakage…………………………....Checkfocusholes are used to rear
sleeve.
If view within limit
These on this frame
A you into the engine from the
with detach the the engine (open).
seconds, nosefor hot
cone.
for 5the reverser deployed surfaces
Caution
at this location ?” fan starts toafter recent flight
rotate…

A small puddle T12 Total Inlet Temperature Sensor
of oil in the engine
exhaustThe oil level indication has a different of a red locking
plug is acceptable. will notice the top
(5 items) You
A large puddle may cause heavy ifengine
scale for the left pin here smoke
and right the reverser is dispatched
and exceptionallyof the wing fire up to
because a tail pipe dihedral
inoperative (locked).
10 minutes after engine shutdown.

 The Walk-Around  Right Wing and Leading Edge

Right Wing and Leading Edge
Picture of cold soaked fuel frost on lower wing
surface. This picture is taken after descent
Exterior Inspection in VMC and landing at an airfield with ambient
Don’t call maintenance to
temperature above 35 °C / 95 °F !!
Access Panels ………………………………… notice there is no ice on the flaps ! fuel
Also Latched Defined cold-soaked
report holes in the leading
edge ! These holes serve
Leading Edges Flaps and Slats ………………. Check frost area painting (NG)
as wing anti-icing air outlet !

Fuel Measuring Sticks …………….. Flush and secure
Wing Surfaces ………………………………….. Check
Fuel Tank Vent …………………………………. Check
(NG) Do you recall the Cold soaked Fuel Frost Limits ?
Additional Information The defueling bay door cannot be
Lower Wing : Max. 3 mm or 1/8 inch if the defueling valve is open.
closed
This valve is Wing anti-icing
Wing Anti-Ice Exhaust ………………………………….duct manually operated
Only on the wing itself, not(shown here).
on the
by a handle air supply
flight controls, LE/TE Flaps/Slats
“What are you looking forwinglets.
and not on
along the leading edge
Upper Wing : Max. 1,5 mm or 1/16 inch Pressure
of the right wing ?” > 0°C or Poppet is flush with the wing
OAT
Check that Flame Arrestor
Valve 32°F
lower skin.
No visible moisture
If the valve is popped wing inwards, it
(5 items) Only within thereset by maintenance.
must be painted area LE slats actuator
Similar on both wings (!)

 The Walk-Around  Right Wing Tip and Trailing Edge

Right Wing Tip and Trailing Edge

Exterior Inspection Picture (NG) : The deflection of
the flight spoilers deploy is less than
Position and Strobe Lights ……………………... Check
the ground spoilers.
On NG with the SFP (Short Field
Static Discharge Wicks …………………………. Check installed, the
Performance) option
Aileron and TE Flaps …………………………….angle is further increased.
deflection Check

Any idea about the number of static
Flight and Ground Spoilers ………………………………
dischargers installed on each wing ?

Main Wing : 4
MEL 33-11 is rather complicated due to
“WhatWing (with looking different plastic lenses (single or dual)
Main are you blended winglets) : 2
for
at this location ?” and winglets installed or not.
As a general rule at least one red and
Horizontal Stabilizer : 3
one green navigation light must operate
for night flight.
(3 items) This picture shows a 737-800 with a dual
Vertical Stabilizer : 4
plastic lens and blended winglets.

 The Walk-Around  Right Main Gear

Right Main Gear

Exterior Inspection

Tires, Brakes and Wheels ……………………... Check
Gear Strut, Actuators and Doors ……………… Check
Gear Pin ………………………………..…… As needed
Hydraulic Lines …………………………………. Secure tire wear limits
Refer to your company manuals
and procedures for
or call maintenance.
Additional Information As a general rule, the strut should be
extended by “3 fingers” with passengers
Brake Temperature……………………………………….
and fuel loaded. brake wear indicator pin
If one
is missing, the brake can stay
in service if operation of the
The aircraft can be pin is satisfactory.
remaining dispatched with
Parking brakes must set in order to check
“What are you looking for one, two If aall three main landing
or pin is broken, just consider
the brake wear indicator pins.
gear doorsmissing… Refer to the
it – option)
(NG missing. both brake pins flush, the
With one or
at the right main landing gear ?”
DDG-CDL forTemppenalties and MFD
Brake fuel display on the rejected takeoff.
brakes can still handle one
maintenance actions.
According to the Maintenance Manual AMM
32-41 you may not leave with a flush pin.
(4 items) Check your company SOP.

 The Walk-Around  Right Main Wheel Well

Right Main Wheel Well
When the hydraulic fluid return filter is
Exterior Inspection Thisclogged, a like a hydraulic pressure
may look red differential fluid
leak…indicator will appear on top of the filter
APU Fire Control Handle …………………...……….°F).the uses over-
(if OAT isMLG uplock mechanism
The above 2 °C – 36
Up
However, what locking toindicator, call fitting is broken,
(NG) If
The flightyou notice thesee here is the main landing
center you red with an
If can be dispatched keepboth
(NG – as installed) NGS light ……………...……theTwo be raised after takeoff.
Check
main wheel gear (dome) lights inoperative landing gear
anti-corrosiveup and locked. associated hold the
well protection compound
maintenance… springs
cannot locked position.
Anyway, uplock hook in doubt, and
if there is any the up
Wheel Well ……………………………………….. Check disappeared (CL) an inoperative inspection
call maintenance.
It has happened that a spring However, on
The FCOM does not specify what to check, (if you found it in your garden, is a NOGO for night flight !
in flight
please return to company)
flood light
(two installed – one for each gear)
so here are some suggestions :

- General condition (no loose cables, no fluid leaks)
- Hydraulic System Quantity, Pressure and Filters
- Landing Gear Up-Lock system
“What are you looking for System both the Fire Handle and the
- (CL) Landing Gear Viewing Verify that
Bottle Discharge Switch are safety wired.
in (NG)Right Main Wheel Well ?”
-
the Loose Thread Frangible Fitting
Verify that the operability green indicator
light is illuminated, unless the NGS is
(6 items) dispatched inoperative.

 The Walk-Around  Right Main Wheel Well

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

 The Walk-Around  Right Aft Fuselage

Right Aft Fuselage

Exterior Inspection

Doors and Access Panels …………….……… Latched
Negative Pressure Relief Door ………..……… Closed Compartment
(NG) Aft Cargo
Outflow Valve …………………………….……… Check Behind this bulkhead is the toilet
Antenna VHF
waste tank and the compressor.
Probes, sensors, ports, vents and drains …….. Check (CL) COMM 3
APU Air Inlet ……………………………………… Open (NG) COMM 2
(CL) APU Fire Bottle …………………...…..…… Check

(CL) Verify that the Squib Discharge disc (yellow)

Additional Information looking
“What are you for and the Bottle Overpressure disc (red) are in place

along the aft fuselage ?” recent delivered (NG) the main service panel is located on
On The water
Toilet Waste System…………………………………..right side (NG) – left side (CL) of
outflow valve comes with “teeth” to
the
Verify the cargo compartment entry picture is (NG).
(6 Comm NG) (7 items reduce aerodynamic noise. the airplane. This
VHF items -Antenna…………………………………..toilet service panel is located on
CL) for any dents… The
the opposite side, with an extra toilet
access panel in the front (CL).

 The Walk-Around  Tail

Tail APU Cooling Air Inlet

Exterior Inspection

Vertical Stabilizer and Rudder ……………..….. Check
Horizontal Stabilizer and Elevator …………….. Check
Elevator Feel Probes …………………………… Check
(400-800-900) Tail Skid ..………………………. Check
Static Discharge Wicks ……………………….... Check
Strobe Light ……………………………………… Check
APU Cooling Air Inlet and Exhaust Outlet ….… Check

around the tail ?”

(8 items) APU Exhaust Outlet

 The Walk-Around  Tail

Tail Location of the VOR/LOC antenna

The famous Stab
Logo Light…………………………………………………
trim jackscrew

Horizontal Stabilizer-to-Body Sliding Seals……………
Antenna HF and VOR……………………………………
The APU inletsteering cables,
The rudder door as seen from the
Now, let’s take a look, where you have inside. This here isflight deck door
connected to the the electric
actuator. pedals.
never been before, inside the tail cone : rudder

Stabilizer Trim system ………………………………..
APU Inlet Door system ……………………………….
Location of the HF antenna
APU Fire Extinguisher system ………………………. or lower seal is
If the upper
The electric Stab trim actuator maintenance.
missing, call
Other …………………………………………………… When dispatched with the
seal removed, apply the
performance weight penalties
(NG) The logo light is powered from
from the DDG / CDL.
The Stab trim Main Bus 1. Hence the logo lights
control cable drum.
The cables are connected to the
The aft pressure bulkhead isilluminate with the CAB/UTIL
do not
flight on 737-100 thruin OFF…!
hemispheric switch 800
deck manual trim wheels.
and flat on the 900

 The Walk-Around  Left side

Left side

Differences with Right Side As a general rule both pressure
indicators should point upwards.
Left Aft Fuselage : When you return to the flight deck, may tend slightly to the left
They
on cold days and slightly to the right
(NG) Waste Compressor Vent …………. Check Very often,days as pressure inside the
take a look at these drains.
on hot
the drains are clogged !
bottles changes with OAT.
These drains guide away rain water that
has entered the cabin through the
Left Main Wheel Well : associated door. A clogged drain may
Fire Discharge Bottles ………………...…. Check into the E&E,
cause rain water to seep
causing damage to electronics.

During the exterior inspection
Additional Information you may notice the sound of
the vacuum compressor
Entry / Service Door Floor Drains …………. toilets.cabin crew flushes
when the
the
Check
“What additional items
will you be checking A malfunctioning air/waste
separator may direct waste
on the left side of the airplane ?” to the air outlet i.s.o. towards
the waste tank…

(2 items - NG) (1 item – CL) So here is a good advice :
stay away from this hole !

Cold Weather Operations
Exterior Inspection – Supplementary Procedures

 Cold Weather Operations

Pay extra attention to the following items :

Surfaces ……………………………………………………………………… Check
Control Balance Cavities …………………………………………………… Check
Pitot Probes and Static ports ………………………………………………. Check
Air Conditioning Inlets and Exits …………………………………………… Check
Engine Inlets …………………………………………………………………. Check
Fuel Tank Vents ……………………………………………………………... Check
Landing Gear Doors ……………………………………………………….... Check
APU Air Inlets ………………………………………………………………... Check

 Cold Weather Operations

Some Pictures :

Clear ice on the leading edge

Ice formation on the engine fan
after a short taxi time

Ice formation in the engine inlet
Ice formation on the pitot tubes

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.

 Top 10 Blunders

Number 10

How about these 3 tools…?

General condition OK ?

 Top 10 Blunders

Number 9

A large dent in the fuselage may
easily go unnoticed…

 Top 10 Blunders

Number 8

Don’t tell me
I didn’t warn you !

 Top 10 Blunders

Number 7

OK, what’s wrong here ?

(NG) The main gear frangible fitting
may never be used to attach the fuel
truck ground wiring cable !

 Top 10 Blunders

Number 6

There 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…

 Top 10 Blunders

Number 5

OK, what’s wrong here ?

This rod is broken, so you will be flying with
the right nose wheel well door open…

 Top 10 Blunders

Number 4

During 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.

 Top 10 Blunders

Number 3

Anything wrong here ?

(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 !

 Top 10 Blunders

Number 2

This 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…

 Top 10 Blunders

Number 1

The (smaller) main wheel of a Boeing 737-500
And our Number 1 winner
mounted on the Boeing 737-400…
today is… ???
So, always take a look to the wheels !


the end
-
for more information

www.B737MRG.net
www.B737.org.uk

Have a
safe
flight !

Slide 40

B737mrg exterior inspection

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