737ng common fault experience summary

Aviation maintenance professionals, share different aircraft fresh things every day!

ATA21 air conditioning boosting system

1. 737-800 Regional Zone Temp lamps or PACK lights on the airplane air conditioning panel (more appearance after sliding out or turning back the power), or after the recall.

Common reasons: Mainly, the regional temperature controller is converted to the power supply, due to the instantaneous electromagnetic interference (EMI), the controller records the Trim Air Valve relay error, the controller records allocated a shutter fault, which is generally reset, the fault light can disappear. .

Treatment measures: Press the main payment of the card, if the PACK light is displayed, repeat the caption, make sure the pack and zone light is off, if it does not disappear, the air conditioner re-reset adjustment switch P6-4: A2 / B3, A9 / A11 (left); B9 / B11 (right) or reclaimed RESET on the controller to ensure that the fault light is off (when test, make sure the Go light is on, press the prefl and verify to confirm the fault, wait for about 1 minute)

2. Equipment cooling gas or exhaust “OFF” light is on

Common reasons: flow sensors (S210N701-43) too dirty or fan low speed

Treatment measures: Clean Flow Sensor (21-27-03), replace the fan

3. Cockpit noise

Common reasons: more silencer failure

Treatment measures: Replace Silencer 214A1103-10 / 11

4. Cockpit, front cabin or rear duct temperature indication is about 0 degrees, it is difficult to rise

Common reasons: Most of the cockpit or cabin temperature sensor is too tit or malfunction

Treatment measures: Clean the corresponding temperature sensor

5. Cabin height is high (climbing, cruise or decline is above CPC plan limit value)

Common reasons: the engine gas supply capacity is lowered, the flow regulation capability of air-conditioning components is reduced or the boom is leaked in the supercharged area (cabin door, cargo door, APU ventilation pipeline and post-pressure separation frame connection, external shutter, ground gas source Car interface, wake water, etc. may be leaking)

Treatment measures: Troubleshooting in the CPC, check the engine air intake, air conditioning capacity, replace the air-opening and air-conditioning capacity, leak inspection of the fuselage (special examination 4.0 psi-2.5psi) Keep time) and repair leakage or replaceable holes

6. Start the engine (especially the right hair) (from the 25% speed lever to the start of 47% speed during the starter), the cabin or the cockpit has kerosene taste, the engine is started, the odor disappears

Common reasons: Check if there is a leakage in the left / right air conditioner unit, the assembly door leakage can lead to slow start time, engine richer, and rich mixer is inhaled by APU, and is loaded with the carrier Entering the airway, the unscrupulous component can enter the cabin.

Treatment measures: Replace the component shutter.

ATA23 communication system

1. Cabin loudspeak machine abnormal play pre-record speech

Common reasons: After the player is modified, the external electromagnetic interference is easy to cause non-normal playback.

Treatment measures: Reset CB P6-1: C9, replace the projector PRAM (or exit the tape in the pre-recording broadcast)

2. The FAIL light on the VHF communication panel is on

Common reasons: more appears on the three VHF communication system aircraft (our company is all three), mainly due to the data of the CMU to Acars, if the amount of data is too large, it will overflow, resulting in the FAIL light on the panel.

Treatment measures: Re-reset CB: P18-2D12 VHF-3

ATA24 power system

1. Power light “elec” bright (air power light is suppressed)

Common reasons: Most of the static translucent (especially a batch of variable flowers produced by 2005) or spare battery failure, part is a battery charger failure

Treatment measures: Reset E5 (P18) after 2 minutes after 2 minutes; Bite test on the power control and indicator panel, confirm the fault piece, long press MAINT electric door, clear fault information history; confirmation failure with the main battery charger Replace converter or battery

ATA27 flying control system

1. “SPD LIM” information is displayed on EFIS, and the auto slat fail is on the time, sometimes it may be accompanied by a moment of shud rod phenomenon.

Common reasons: SYMD software problem, resulting in SYMD to make Bite display AOA input fault (but actual AOA is generally no fault), software upgrade to 285A1010-7 or 107 SYMD will integrate AOA and Adiru’s welcome signals.

Treatment measures: Do SYMD test, look up the displayed fault code.

ATA28 fuel system

The “Spar Valve Closed” light is on or the Cross “Valve Open” light, sometimes the corresponding hop switch B3, B4 or B7 (P6-3) also jumps out, but the engine is working properly.

Common reasons: engine fuel off a shutter or transportable live electric motion cartridge (S343T003-39) Easy water gas results in a short circuit (upgrade to S343T003-39 / 56B / 66 will reduce the occurrence of this problem)

Treatment measures: Object execution confirms the normal M program (when the rod confirmation is opened, the fire handle is confirmed) is released, the replacement or door is replaced by the door (the outer side of the root engine)

ATA29 hydraulic system

1. EMDP jump off, sometimes it can smell the hydraulic oil in the cabin and cockpit

Common reasons: add too much hydraulic oil or oil filter too dirty to cause unidirectional shutters

Treatment measures: Add an appropriate amount of oil (excess hydraulic oil) as specified. Replace oil filter.

ATA30 anti-ice system

When using anti-ice, the engine anti-ice shutter fault light “COWL ANTI-ICE” is bright (more appears in high power)

Common reasons: When low power, it indicates that the door is not open, the position of the electric door is faulty or the active door, high power, indicates that the shutter downstream pressure is overpressive, and the door-to-door regulator is blocked by the booty. (-4 can be high) .

Treatment measures: Object is locked according to the actual situation (when there is ice weather, but also lock 9th HPV), or lock it in the position, replace the anti-ice shutters after the air.

2. Big wings anti-ice shutter fault light “Valve open” bright (engine high power or low power)

Common reasons: more temperature sensor failures or warming controller faults, side windshields also have sectors to malfunction due to the problem of electrical tetles of the helix (before SB737-300-1058), partial jump off-off strip leads to no power supply

Treatment measures: Check and reset the P6-11B9 and P6-12B8 skip switching, for the front windshield, convert the electric door in the electronic device cabin, change the sensor used, for the side window, the spare sensor is changed in the windshield, and it is determined whether or not the sensor fault, By performing Bite testing in the warming controller, the test does not display the fault can consider the string controller to determine, the replacement windphone should be determined according to the manual to determine the terminal after the windshield is measured.

3. Windmills warm sunlight “ovheat” bright or wind bar does not warm (ON lamp is not bright)

ATA31 instructions and recording systems

The flight rudder field on the DU did not indicate

Common reasons: more appearance during taxi check

Treatment measures: reset skip switch P18-2C9 / C10 or P6-1 E12 (MEL can release)

2. FDR OFF fault light is on, Overhead light on the warning sign is also bright.

Common reasons: Multi-happening when the ground is converted (such as starting the engine), the FDAU itself or the FDAU software can cause the OFF fault light (Note the part number of the FDAU is the same as 737-300, but the software version is different, so can not be mixed )

Treatment measures: In the case where the flight is not affected, it is first inspected on the DFDAU on the DFDAU. It is a FDAU’s indicator that is bright. If the FDAU’s indicator is on, the self-test is performed on the FDAU panel, find further fault information, Confirm the cause of the failure. Then reset the jump switch P18-2: C9 / C10

3. Slightening takes the test when the throttle

Common reasons: Most of the operating airfoil is not in the takeoff configuration bit, especially the speed brake handle is not in the next card.

Treatment measures: Query fault information and code in the current or historical fault menu, confirm the error configuration settings in the fault, perform the electric door to the error configuration setting, and turn the takeoff warning test, confirm the flying sound warning system Work is normal.

ATA32 landing gear system

The “PSEU” light on the top plate is on the top plate (sometimes accompanied by “RA” fault flag on EADI (see FTD-34-03001 and SL32-141)

Common reasons: Most of the logic confusion (upgrade to -5 can reduce this phenomenon), common causes include the high signal provided by Emergency Gate, RA1 (or FCC) incorrectly, ground spoiler control the door, flaps take off or Landing warnings S138 / S245 (easy to short circuit due to design defects), PSEU itself software logic or hardware failure, etc.

Treatment measures: First confirm that the PSEU light can be made by pressing the master caution, Recall, if the PSE is turned off (the PSEU records the fault you can release, the PSEU upgraded to -5, if the engine shutdown or set the PSEU lamp You can release the fault that can be released, and you cannot go out to enter the PSEU’s current troubleshooting page to find the fault code, determine the cause of the fault, replanize the PSEU, or replace the fault piece, make sure the PSEU light is off

2. Automatic brake release (DISARM) light is bright (sometimes lighted the lamp when testing on the panel)

Common reasons: Most of the AACU or panel fault (including internal release relays), if only OFF is bright to be a valve component failure, part is fake information. Board lamp is on, the automatic brake relief lamp is also bright.

Treatment measures: Make a AACU’s Bite test (anti-strain / automatic brake test), confirm the fault information, according to the FIM Task trim The door connector D2572 confirms whether the light is destroyed, (Note: Confirm the aircraft configuration before making Bite). Fake information can be reset P6-3: E16 / E18, A16 / A18

3. Failure when the anti-strain brake (INOP) light is on

Common reasons: multiple AACUs, sensory relays (internal, external, spare) and spare brakes to choose pressure on the door

Treatment measures: Do AACU’s Bite test (anti-brake / automatic brake test, do Bite before confirming the aircraft configuration settings) Reset P6-3: E16 / E18, A16 / A18

4. During the landing process, the landing gear is placed in place, and the red light is still bright (mostly the intermittent bright) standby indication green light is normal, after retreat, red light is lighter

Common reasons: After the handle of the landing gear accumulates, the friction is increased, causing the handle to pull down, there is no accurate handle to put the electric door (S2) BACS30BV1

Treatment measures: Clean the lubrication handle assembly mechanism to ensure flexible handle, if there is a number of faults, replace the handle assembly (273A3301-4, -6, -8)

ATA34 navigation system

The radar invalid “WXR Fail” and “PWS Fail” information in the air or the ground are displayed, or no image display is displayed, or the normal red weather image is displayed in flight.

Common reasons: main reasons for display data issues, the radar transceiver itself does not fault, part is the transceiver fault, especially the part number of Collins is 622-5132-633 and 822-1710-001 (according to the repair report, vast majority Fail-free)

Treatment measures: After the WXR adjustment switch D13 (P6-1) 90s reset, or clean the reloader transceiver, replace the transceiver, inform the unit: If the manual adjustment gain in the air leaves CAL, the radar sensitivity will increase the image Re-switch radar to reset antenna angle, automatic bit conversion of human position compare meteorological images.

737ng common fault experience summary

Common reasons: more temperature sensor failures or warming controller faults, side windshields also have sectors to malfunction due to the problem of electrical tetles of the helix (before SB737-300-1058), partial jump off-off strip leads to no power supply

Treatment measures: Check and reset the P6-11B9 and P6-12B8 skip switching, for the front windshield, convert the electric door in the electronic device cabin, change the sensor used, for the side window, the spare sensor is changed in the windshield, and it is determined whether or not the sensor fault, By performing Bite testing in the warming controller, the test does not display the fault can consider the string controller to determine, the replacement windphone should be determined according to the manual to determine the terminal after the windshield is measured.

2. Display “Terr Fail” information on the navigation page, sometimes GPWS INOP lights

Common reasons: EGPWC fault (including software failure), the fault rate of 965-0976 / 1690-34-97 is higher, after completing SB965-1690-50 OR 965-1690-52, EGPWC failure rate reduce

Treatment measures: Reset adjustment P18-1: A7 / B7, perform Bite testing for EGPWC, confirm that the fault indicator further confirms the fault piece

3. Only one side ND has radar display

Common reasons: Terrain / WXR Relay fault

Treatment measures: You can transfer the Efis CP failure phenomenon, don’t blindly determine the failure of the EFIS control board!

4. The Take Off page is not OAT input box on the Take OFF page, and the automatic oil door is not connected.

Common reasons: If the TAT of the DU indicates blank, the FMC believes that there is no real environment temperature comparison, causing a Take OFF page without oat input box.

Treatment measures: Check if the TAT indication of the DU is normal, not normal to pull the bit CB (if you turn on the atmospheric data probe on the ground, the TAT itself is overheating, so that the TAT indicates the blank, and the OAT input is checked again after warming. frame)

5. The height of the CDS and the standby height display is inconsistent

Common reasons: The precision of the spare height table itself does not have a high electronic height, and it may be drift after a period of time.

Processing measures: First, refer to the Fim Task 34.13 form to determine whether the difference is exceeded, if the target is exceeded, replace the standby height table

6. CDS Displays Display Source Information

Common reasons: more settings errors

Treatment measures: Check if the DISP SOURCE knob is located in the Auto bit.

7. GPS unilateral or double-sided no signal

Common reasons: often appeared in the bridge. It is easy to cause signal reception in special position.

Treatment measures: The aircraft automatically returns to normal after the plane is in Hong Kong.

8. After the unit presses the recall, the inertial light IRS light on the left main warning card is on

Common reasons: Under normal circumstances, if it is not inertial, the IRS lamp is destroyed after re-pressing the main police bill. Most of the main alarm is correct), confirm the fault information, according to the FIM trim, if there is no fault information, check the standby brakes to choose the shutter, the fake information reset P6-3: E16 / E18, A16 / A18

ATA36 air pressure booster system

1. Low exhaust pressure of the engine (high power or low power)

Common reasons: low power is HPR or HPV: 107484-6 fault, high-power is more pre-cooler shutters 3289562-5, 390 temperature controller 129666-2 or air pressure regulator 3214552-5 fault, due to mounting base Vibration leads to the pressure of the pressure regulator to release the air leakage to cause low air pressure

Treatment measures: After confirming the pressure of low pressure, confirm the replacement component, or check whether the ventilation pressure regulator has leakage, replacing the gas-opening regulator, 390 degree temperature sensor failure High rate

2. Engine ventilation jumps “Bleed Trip OFF”

Common reasons: more high-power pre-cooler valve or 390 temperature sensor failure

Treatment measures: Replace the pre-cooler shutter or 390 temperature sensor

ATA38 water system

1. The toilet sewage system does not work before the ground

Common reasons: vacuum pump does not work, resulting in 16,000 ft below the toilet waste box cannot be exhausted

Treatment measures: Ground reset electronic cabin PDP1 (p91) C11 and F2 jump switch, if it is not in effect, the vacuum pump is replaced.


1. The air intake pressure of the APU is zero

Common reasons: Most of the pressure differential sensor failure

Treatment measures: Today’s CDU’s APU maintenance page, find the fault code of the APU, determine the cause of the fault

2. APU maintenance light “MAINT” bright

Common reasons: Most of the rectifier diode faults in the amount of the APU oil or the starter generator (see SL-737-49-058D)

Treatment measures: In the CDU, do the APU’s Bite test. Find fault code through the current page, confirm the cause of the failure, most of the needs of the need for the need to work on the APU oil, the hardenense back light is not destroy the starter generator

3. APU ground can’t start success

Common reasons: APU boot conversion assembly (SCU) is a multi-fault piece

Treatment measures: Replace SCU

4. APU ground automatic shutdown, APU’s “fault” light is on

Common reasons: oil filter is easy to block, the external temperature is too low affecting the APU intake combustion (at this time, the air intake pressure suddenly decreases or returns to normal)

Treatment measures: In the CDU, the APU’s Bite test is found. Find fault code in history page, confirm the cause of the fault, the oil filter is highlighted, and it is necessary to change the oil and oil filter, the weather is too cold. Can be started

ATA73 engine fuel and control

1. Ground engine control light “Engin Control” bright (the air is suppressed)

Common reasons: There is a fault that cannot be released inside the engine, mostly lost control channels when the dual channel or single channel is working (EEC is dead, the airplane is air, the fault light is not bright)

Processing measures: Enter the CDU Maintenance page, find current fault information and code, and check and test the fault of the record, confirm that the fault light disappears (sometimes passing multiple trials can disappear)

2. Air engine spare mode light “altn” bright

Common reasons: The engine loses the PT signal given by the ADIRU, so that the engine is in a soft standby mode or hard back mode, it is necessary to press another EEC lamp to ensure that both parties are in standby mode control.

Processing measures: Enter the CDU maintenance page, find the current fault information and code, and test the LRU of the recorded fault, confirm that the fault light disappears, the possibility of the ADIRU and DEU faults are relatively large.

3. High-pressure fuel on the fuel control panel when the engine works “Engin Valve CLSED” light is on (the door is not open, the door is normal)

Common reasons: HPSOV’s positional electricity failure inside HMU does not correctly indicate the location of the shutter, in some cases, the electric shutter assembly package of the starting rod (providing the command signal) will also be indicated by the problem of the HPSOV input signal.

Treatment measures: Clean HMU’s electrical tape and EEC electrical tape J5 / 6, pay attention to measurement line confirmation is replacement

HMU (P6-3: E5 / E6) (73-21-10), or start the electric shutter assembly (AMM76-11-11)

4. Engine fuel on the fuel panel “Fuel Filter Bypass” light

Common reasons: more fuel filters are quick to block or differential difference failures

Treatment measures: generally need to change the fuel filter and fuel pressure difference (high failure rate, possibly cause IFSD)

ATA74 ignition system

1. Left or right mesh failure

Common reasons: often see when starting the engine

Treatment measures: Left ignition failure is directly released; the right mesh is invalid, according to the AMM74-00-00-750-801-F00 Isolation is not an EEC body failure; then according to AMM74-00-00-040-801-F00 Removal Lower package, left point fire cable to connect to the right mesh excitation release (new MEL’s terms)

ATA76 engine control

1. EEC intermittent record fault code: 73-x145n & 73-x146n

Common reasons: TLA throttle is over-limit or the position of the A and B channel throttle, mostly in contact with the electrical joints of the fuselage and the big wing

Treatment measures: Keep inspection of the electrical tap (refer to WDM73-21-21) at the fitting of the wing, clean and tighten the joints here, LH: DM9 / 11; DM25 / 27 RH: DM10 / 12; DM26 / 28

ATA77 engine instructions

1. The engine vibration value is large at a corresponding speed, generally exceeding 2.0 or more (but no more than 3.4)

Common reasons: The engine itself is a widopine blade, susceptible to blade lubrication and isolation and closing of isolation, vibration value is easy to be large.

Treatment measures: For the vibration value of more than 2.0-2.5, it is often necessary to make both the lubricant blades to be flattened, and the single leveling is difficult to reduce the vibration value to a relatively low level.

2. After the motor vehicle, the N1 / N2 / EGT indicator appears red frame on the table.

Common reasons: If the pilot does not reflect the real N1 overrun situation in the air, more logical confusing is logically confusing and records overrun processing measures: Enter the CDU Overliminations Menu AINT> Engines> Exceedances, view N1 / N2 / EGT red line value Record, confirm the time of over-limit, if you appear before the shutdown, query the fault code truth; if the overlightext appears after the mutual car, you can event> Sreset, if you can’t clean it, reset the DEU1 / 2 Skip switch ( DEU1 P18-2: D5 and P6-1: D10; DEU2 P6-1: D9 / D11)

3. Failed code was found when the engine was tested in the CDU.

Common reasons: Common fault code is more than one component failure, N2 speed sensor fail, TBV or FMV control overrun, etc.

Treatment measures: Test the corresponding components and confirm the normal work, otherwise replace the corresponding LRU.

ATA78 engine exhaust

1. The board on the P5 of the engine “Reverse” light is bright

Common reasons: EAU detects and records DCV, HIV and anti-push lock, anti-push

The position is not in line with the actual position, and the position fluctuations of the hydraulic assembly shutter or the position sensor in which the internal position sensor oil or water vapor shortage is caused, and some are the EAU failure.

Treatment measures: Find the corresponding bright fault light on EAU, press or release the fault light button to keep 2 wonderful, record the fault light code; press the corresponding side EAU to reset the button 2s, if it is reversed, it must be After the reverse push (at least the anti-push handle pull out) and press the reset, the record still keeps the bright fault light, if all the lights are off, re-put the anti-push to ensure that the anti-push fault lamp is after the 10.5s after receiving the command Replace EAU.

ATA79 oil oil system

1. DU oil absorbing light “Oil Filter Bypass”

Common reasons: Most of the oil filter is quick to block or differential differences (if there is a possible manual stop in the air)

Treatment measures: Generally, it is generally replaced simultaneously to the slip oil filter and the oil pressure difference electric shutter.

2. After the engine is cold or the engine is parked, there is more oil tube.

Common reasons: The oil tank of the engine is sealed with a pneumatic castor. When there is an oil and gas separator in the oil tank, when the engine is low-speed, the air pressure of the castor is small, and the splitter of the separator is also small, so the oil is partially over castor. Tooth and enter the ventilation through the oil and gas separator

Treatment measures: Confirm that the oil does not continue to leak, and does not leak when the engine is high power

3. When the motor is the car, the engine oil pressure on the lower DU is vertically indicated.

Common reasons: Most for the launching car, the EEC gives the low voltage signal, causing the DEU2 error to show the oil pressure in the lower DU.

Treatment measures: Convert the DEU source selection switch on the P5 board to DEU1, confirm the failure; self-test on the EEC on the CDU, check whether the fault disappears; if you do not disappear Reset DEU 2 Jump switch (P6-1: D9 / D11) Otherwise replace DEU2 (best waiting for 5 minutes)

4. Precursor residual port seepage oil (more than about 60 drops per minute)

Common reasons: After the 3rd bearings are TEFLON composites, the adhesive is not easy to degenerate due to high performance, which cannot be confirmed by the aperture (after the engine upgrade modification).

Treatment measures: Continuously monitor the leakage of the engine oil and the oil consumption of the engine, confirm the excerpt, need to replace the engine.

ATA80 boot system

1. The engine starter cannot be automatically disengaged at 55% N2 speed.

Common reasons: Most of the starting electric horses keep the electromagnetic coil failure, some DEU faults

Treatment measures: Replace the starting electric door

2. Start the engine when starting the engine

Common reasons: the dish valve in the door is not sensitive, common in the preference

Treatment measures: Check if the jump switch jumps out of the left P18-2 B8 right Sending P 6-2 C4 to manually do moving the door several times with big wrench (all of which must be turned off) and turn it again. MEL can be released outside the station, but it is not easy to operate.