Boeing 737 - 600/700/800/900. Operations Manual (1997 year)

Operations Manual Bulletin No. TBC-15, Dated January 29, 1999 (continued)

For single FMC installations:

• VTK flag, if navigation display is in MAP or CTR MAP mode

• Amber FMC light on pilots’ instrument panels

• LNAV and VNAV disconnect

• CDU installation - “FMC” displayed on CDU for approximately 5 seconds

• MCDU installation - MCDU display reverts to MENU page, initially

without “<FMC” prompt

For dual FMC installations:

Left FMC restart indications:

• VTK flag if Captain's navigation display is in MAP or CTR MAP mode

• Amber FMC light on pilots’ instrument panels

• LNAV and VNAV disconnect if FCC A is in CMD or is the master F/D

• CDU installation - “FMC” displayed on CDU for approximately 5 seconds

• MCDU installation - MCDU display reverts to MENU page, initially

without “<FMC” prompt

Right FMC restart indications:

• VTK flag if First Officer's navigation display is in MAP or CTR MAP mode

• Momentary amber FMC light on pilots’ instrument panels (displayed for at

least 4 seconds)

• LNAV and VNAV disconnect if FCC B is in CMD or is the master F/D

• FMC CDU message “SINGLE FMC OPERATION”, which may clear after

4 seconds

Service Bulletin 737-34A1502, provides information on the U10.2A software

upgrade that fixes the anomaly.

Operating Instructions

While in the descent phase of flight, flight crews should not make modifications

to the flight plan on the ACT RTE LEGS or ACT RTE page and then press the

DES key before predictions have completed processing. Approximately 10

seconds elapsed time after EXECuting the modification or display of destination

ETA on the CDU PROGRESS 1/3 page indicates processing completion.

If a program fault software restart occurs, LNAV and VNAV are not available. Use

conventional means of navigation until the restart is complete and navigation

indications have returned to normal.

Page 2 of 4

Operations Manual Bulletin No. TBC-15, Dated January 29, 1999 (continued)

The following procedures may help speed the recovery from a program fault:

For single FMC equipped airplanes:

• The FMC will be unusable for 6 - 8 minutes.

• When the FMC CDU POS REF 2/3 page indicates an FMC groundspeed

(GS) of 80 kts or greater, a position shift to an IRS position should be

executed on the POS SHIFT 3/3 page.

For dual FMC equipped airplanes:

• If one or both FMCs experience a program fault, cycling the FMC source

select switch to a different source for 10 seconds will restore the FMC

groundspeed to the correct value.

FMC navigation is restored when the FMC groundspeed is within 20 kts of the

IRS groundspeed. FMC and IRS groundspeeds are displayed on the CDU POS

REF 2/3 page. After the FMC recovers, the RTE LEGS page will display an

inactive route with a SELECT ACTIVE WPT/LEG message. Select the

appropriate active waypoint and resume FMC navigation.

Administrative Information

Insert this bulletin behind the Operations Manual Bulletin Record page in

Volume 1 of your Operations Manual. Amend the Operations Manual Bulletin

Record to show bulletin TBC-15 “In Effect” (IE).

This condition is temporary until Service Bulletin 737-34A1502 is installed.

CS3-2777

Page 3 of 4

Sect Name

Section Name

Operations Manual Bulletin

for

The Boeing Company

Seattle, Washington 98124-2207

Number: TBC-16R1

Date: April 16, 1999

Document Effectivity: D6-27370-TBC

Subject: IMPROPER AUTOTHROTTLE THRUST SETTING DURING GO-

AROUND AFTER ASSUMED TEMPERATURE DERATED

TAKEOFF

Reason: This is a reissue of TBC-16, dated March 3, 1999, which informed flight

crews of operational issues associated with an FMC/Autothrottle

interface anomaly. The purpose of this reissue is to provide additional

information about the anomaly.

Information in this bulletin is recommended by The Boeing Company, but may not be FAA approved

at the time of writing. In the event of conflict with the FAA approved Airplane Flight Manual (AFM),

the AFM shall supersede. The Boeing Company regards the information or procedures described

herein as having a direct or indirect bearing on the safe operation of this model airplane.

THE FOLLOWING PROCEDURE AND/OR INFORMATION IS EFFECTIVE UPON RECEIPT

Background Information

In 737-600/-700/-800 airplanes, after a reduced thrust takeoff is performed using

the assumed temperature method, the autothrottle may not advance thrust to the

rated go-around thrust setting when requested to do so. The FMC applies the

assumed temperature reduction to the go-around rating sent to the autothrottle for

the duration of the flight if a cruise altitude of approximately 15,000 feet is not

achieved during the flight. During approach, with the first TO/GA switch

activation, the autothrottle may not advance to the correct go-around thrust to

meet climb rate requirements (1000 - 2000 FPM). In addition, full rated go-around

thrust settings will not be available from the autothrottle with the second TO/GA

switch activation. However, in all cases, the go-around thrust setting reference

displayed to the flight crew on the N1 indicator will be correct and full rated go-

around thrust will be available by manually advancing the thrust levers to

maximum rated thrust.

This situation does not occur after a full thrust takeoff or if the takeoff is

performed using only a fixed derate. Additionally, if a fixed derate is further

reduced using the assumed temperature method, the FMC will apply the assumed

Page 1 of 2

Operations Manual Bulletin No. TBC-16R1, Dated April 16, 1999 (continued)

temperature reduction to the fixed derate thrust during the takeoff phase of flight.

Both the fixed derate and the assumed temperature thrust reduction will then

gradually decrease until full rated thrust is restored at approximately 15,000 feet.

On approach, the FMC will apply the full thrust rating for the engine and send this

value to the autothrottle for go-around.

Operating Instructions

Operators should implement one or more of the following crew procedures until

the 737-600/-700/-800 FMC software has been modified to correct this anomaly:

• Crews should closely monitor autothrottle function and manually

override when required.

• Use only manual thrust setting techniques for go-around if an assumed

temperature thrust reduction was selected at the departure airport and

the airplane has not climbed above 15,000 feet.

• Use only fixed derates for reduced thrust takeoffs.

Administrative Information

This bulletin replaces bulletin TBC-16, dated March 3, 1999. Discard bulletin

TBC-16. Revise the Bulletin Record page to show TBC-16 as “Cancelled”

(CANC).

Insert this bulletin behind the Operations Manual Bulletin Record page in

Volume 1 of your Operations Manual. Amend the Operations Manual Bulletin

Record to show bulletin TBC-16R1 “In Effect” (IE).

This condition is temporary until the system is modified. This bulletin will be

revised to include Service Bulletin information when available.

CS3-2796

Page 2 of 2

Sect Name

Section Name

Operations Manual Bulletin

for

The Boeing Company

Seattle, Washington 98124-2207

Number: TBC-17R1

Date: November 6, 2000

Document Effectivity: D6-27370-TBC

Subject: CONTROL WHEEL MICROPHONE/INTERPHONE SWITCH

ANOMALY

Reason: This is a reissue of TBC-17, dated March 19, 1999, which informed

flight crews that the position of the Control Wheel Microphone/

Interphone switch can prevent PA announcements from the flight deck.

The purpose of this reissue is to add Service Bulletin information.

Information in this bulletin is recommended by The Boeing Company, but may not be FAA approved

at the time of writing. In the event of conflict with the FAA approved Airplane Flight Manual (AFM),

the AFM shall supersede. The Boeing Company regards the information or procedures described

herein as having a direct or indirect bearing on the safe operation of this model airplane.

THE FOLLOWING PROCEDURE AND/OR INFORMATION IS EFFECTIVE UPON RECEIPT

Background Information

An operator recently reported an anomaly while attempting a PA announcement

using the audio panel PTT switch with the Control Wheel Microphone/Interphone

switch latched in the INT (flight interphone) position. If the Control Wheel

Microphone/Interphone switch is latched in the INT position and the associated

audio panel PTT switch or hand microphone is used with the PA Transmitter

Select switch selected, transmissions cannot be made on the PA system.The aft

aisle PA handset or PA hand microphone continue to function normally in this

condition. The other pilot’s PTT switch and hand microphone operate normally if

the associated Control Wheel Microphone/Interphone switch is not also latched in

the INT position.

Boeing Service Bulletin 737-23-1157 provides information on the upgrade that

fixes this anomaly.

Page 1 of 2

Operations Manual Bulletin No. TBC-17R1, Dated November 6, 2000 (continued)

Administrative Information

This bulletin replaces bulletin TBC-17, dated March 19, 1999. Discard bulletin

TBC-17. Revise the Bulletin Record page to show TBC-17 as “Cancelled”

(CANC).

Insert this bulletin behind the Operations Manual Bulletin Record page in

Volume 1 of your Operations Manual. Amend the Operations Manual Bulletin

Record to show bulletin TBC-17R1 “In Effect” (IE).

This bulletin will be cancelled after Boeing is notified that all affected airplanes

in your fleet have been modified by Service Bulletin 737-23-1157. If you do not

plan to modify all your airplanes and would like to have the contents of this

bulletin incorporated in your Operations Manual, please advise Boeing

accordingly.

Please send all correspondence regarding Operations Manual Bulletin Status to

one of the following addresses:

Mailing Address Manager, Flight Technical Publications

737 Model

Boeing Commercial Airplane Group

P.O. Box 3707 MS 20-89

Seattle, WA 98124-2207

USA

Fax:

(206) 662-7812

Telex:

329430 Station 627

SITA:

SEABO7X Station 627

E-mail:

FlightTechnicalPublications@Boeing.com

CS3-2791

Page 2 of 2

Sect Name

Section Name

Operations Manual Bulletin

for

The Boeing Company

Seattle, Washington 98124-2207

Number: TBC-18R2

Date: November 1, 2001

Document Effectivity: D6-27370-TBC

Subject: NUISANCE ZONE TEMP LIGHT ILLUMINATIONS ON 737-800

AIRPLANES

Reason: This is a reissue of TBC-18R1, dated December 11, 2000, which

informed flight crews of operational issues associated with nuisance

ZONE TEMP light illumination during preflight procedures. The

purpose of this reissue is to provide amplification of Normal Preflight

and Shutdown procedures.

Information in this bulletin is recommended by The Boeing Company, but may not be FAA approved

at the time of writing. In the event of conflict with the FAA approved Airplane Flight Manual (AFM),

the AFM shall supersede. The Boeing Company regards the information or procedures described

herein as having a direct or indirect bearing on the safe operation of this model airplane.

THE FOLLOWING PROCEDURE AND/OR INFORMATION IS EFFECTIVE UPON RECEIPT

Background Information

Many 737-800 operators have reported intermittent illumination of one, two or all

three air conditioning system ZONE TEMP lights on the forward overhead panel

during master caution recall. Subsequent maintenance interrogation of the

pack/zone temperature controllers typically shows no faults or occasionally, trim

air valve(s) faults. Resetting the master caution system extinguishes the ZONE

TEMP light(s). A telex was sent to the operators that provides a workaround to

prevent, or at least reduce the number of nuisance ZONE TEMP lights. This

alternate procedure was coordinated with Service Engineering, Environmental

Control Systems (ECS) Engineering and ECS vendor, Allied Signal.

The root cause of the problem has been associated with turning the Battery switch

OFF while the Trim Air switches remain ON and ground power is applied to the

airplane. With the Battery switch OFF, the Trim Air valves are not powered, and

the Zone Temp Controllers remain powered. The result can be a ZONE TEMP

light on master caution recall.

Page 1 of 2

Operations Manual Bulletin No. TBC-18R2, Dated November 1, 2001 (continued)

Service Bulletin

737-21-1133, to be released December 14, 2000, provides

information for the hardware upgrade that fixes the ZONE TEMP light nuisance.

Operating Instructions

After landing, turn the Trim Air switches OFF prior to turning the Battery switch

OFF during the Secure Procedure. Prior to Engine Start turn the Trim Air switches

ON after turning the Battery switch ON

(follow the normal Flight Deck

Preparation - First Officer Procedure).

This procedure is temporary until system modifications are complete.

Administrative Information

This bulletin replaces bulletin TBC-18R1, dated December 11, 2000. Discard

bulletin TBC-18R1. Revise the Bulletin Record page to show TBC-18R1 as

“Cancelled” (CANC).

Insert this bulletin behind the Operations Manual Bulletin Record page in

Volume 1 of your Operations Manual. Amend the Operations Manual Bulletin

Record to show bulletin TBC-18R2 “In Effect” (IE).

This bulletin will be cancelled after Boeing is notified that all affected airplanes

in your fleet have been modified by Service Bulletin 737-21-1133. If you do not

plan to modify all your airplanes and would like to have the contents of this

bulletin incorporated in your Operations Manual, please advise Boeing

accordingly.

Please send all correspondence regarding Operations Manual Bulletin Status to

one of the following addresses:

Mailing Address Manager, Flight Technical Publications

737 Model

Boeing Commercial Airplane Group

P.O. Box 3707 MS 20-89

Seattle, WA 98124-2207

USA

Fax:

(206) 662-7812

Telex:

329430 Station 627

SITA:

SEABO7X Station 627

E-mail:

FlightTechnicalPublications@Boeing.com

CS3-2807

Page 2 of 2

Sect Name

Section Name

Operations Manual Bulletin

for

The Boeing Company

Seattle, Washington 98124-2207

Number: TBC-19

Date: June 10, 1999

Document Effectivity: D6-27370-TBC

Subject: 737-600/-700/-800 ELEVATOR TAB OPERATIONAL LIMITATIONS

Reason: To inform flight crews of operational limitations associated with elevator

tab inspection requirements.

Information in this bulletin is recommended by The Boeing Company, but may not be FAA approved

at the time of writing. In the event of conflict with the FAA approved Airplane Flight Manual (AFM),

the AFM shall supersede. The Boeing Company regards the information or procedures described

herein as having a direct or indirect bearing on the safe operation of this model airplane.

THE FOLLOWING PROCEDURE AND/OR INFORMATION IS EFFECTIVE UPON RECEIPT

Background Information

As a result of structural damage to an elevator tab rod fitting discovered on an in-

service 737-800 airplane, the FAA has issued an Airworthiness Directive (AD)

requiring operators to perform inspections and modifications of this part. The AD

will require an operational limitation on certain 737-600/-700/-800 airplanes until

inspections and modifications detailed in service bulletin SB 737-55A1068 are

complete. This service bulletin calls for inspection within 10 days and has

instructions for an interim fix and ongoing inspections.

Boeing analysis has confirmed that the damage was aggravated by speedbrake

induced airframe vibrations. The severity of this vibration can be reduced by

restricting the maximum airspeed with speedbrakes extended. Since this airspeed

restriction adversely affects the airplane’s ability to descend rapidly, the maximum

cruise altitude must also be reduced to meet FAA emergency descent oxygen

requirements.

The AD and this bulletin apply to airplanes with manufacturer’s line numbers 1

through 190. Airplanes with service bulletin SB 737-55-1063 installed are not

affected. Service bulletin SB 737-55-1063 calls for replacement of the tab mast

fitting with a new part.

Page 1 of 2

Operations Manual Bulletin No. TBC-19, Dated June 10, 1999 (continued)

Operating Instructions

Do not operate airplanes affected by this bulletin at speeds in excess of 310 knots

IAS with speedbrakes extended. Do not operate these airplanes above FL 390.

This procedure is required within 24 hours of AD release and is temporary until

service bulletins SB 737-55A1068 or SB 737-55-1063 are complete.

Administrative Information

Insert this bulletin behind the Operations Manual Bulletin Record page in

Volume 1 of your Operations Manual. Amend the Operations Manual Bulletin

Record to show bulletin TBC-19 “In Effect” (IE).

This bulletin will be cancelled after Boeing is notified that all affected airplanes

in your fleet have been modified by either SB 737-55A1068 or SB 737-55-1063.

Please send all correspondence regarding Operations Manual Bulletin Status to

one of the following addresses:

Mailing Address

Manager, Flight Technical Publications

737 Model

Boeing Commercial Airplane Group

P.O. Box 3707 M/C 20-89

Seattle, WA 98124-2207

USA

Fax:

(206) 662-7812

Telex:

329430 Station 627

SITA:

SEABO7X

CS3-2819

Page 2 of 2

Sect Name

Section Name

Operations Manual Bulletin

for

The Boeing Company

Seattle, Washington 98124-2207

Number: TBC-20

Date: April 17, 2000

Document Effectivity: D6-27370-TBC

Subject: VHF RADIO USE FOR ATC GROUND OPERATIONS

Reason: To inform flight crews of the recommendation to use the VHF radio

connected to the top of fuselage antenna for primary ATC

communications on the ground.

Information in this bulletin is recommended by The Boeing Company, but may not be FAA approved

at the time of writing. In the event of conflict with the FAA approved Airplane Flight Manual (AFM),

the AFM shall supersede. The Boeing Company regards the information or procedures described

herein as having a direct or indirect bearing on the safe operation of this model airplane.

THE FOLLOWING PROCEDURE AND/OR INFORMATION IS EFFECTIVE UPON RECEIPT

Background Information

As a result of antenna location, several operators have reported blanking or

inability to use the VHF radio connected to the bottom of fuselage antenna for Air

Traffic Control

(ATC) communications during ground operations at certain

locations. The investigation of these reports indicated that blocking of the signal

to the lower antenna caused the temporary loss of communications while on the

ground. This blocking can be caused by the airplane not having line of sight to the

tower due to the airplane fuselage, other airplanes or airport topography.

This issue will be addressed in a Federal Aviation Administration

(FAA)

Airworthiness Directive. Boeing has sent a telegraphic Service Letter to all

operators and will create an Alert Service Bulletin to address retrofit of delivered

airplanes. The Alert Service Bulletin is scheduled for release by second quarter

2000 and will direct the reconnection of the antennas to the following positions:

• VHF 1 to top center fuselage antenna

• VHF 2 to bottom aft fuselage antenna

• VHF 3, if installed, will remain in the bottom forward position.

In addition, Boeing is processing a change in production to reconnect the VHF

antennas as described above.

Page 1 of 2

Operations Manual Bulletin No. TBC-20, Dated April 17, 2000 (continued)

Operating Instructions

Use the VHF radio connected to the top of fuselage antenna for primary ATC

communications on the ground.

Operations Manual Information

Attached are the replacement pages which reflect the revised information.

Remove the pages listed below and replace with the attached pages to your

Operations Manual.

Remove Page No.

Date

Insert Page No.

Date

L.0.1 - L.0.2

January 28, 2000

L.0.1 - L.0.2

April 17, 2000

L.10.3 - L.10.4

January 28, 2000

L.10.3 - L.10.4

April 17, 2000

Administrative Information

Insert this bulletin behind the Operations Manual Bulletin Record page in

Volume 1 of your Operations Manual. Amend the Operations Manual Bulletin

Record to show bulletin TBC-20 “Incorporated” (INC).

This bulletin will be revised to include Service Bulletin information when

available.

CS3-2893

Page 2 of 2

Sect Name

Section Name

Operations Manual Bulletin

for

The Boeing Company

Seattle, Washington 98124-2207

Number: TBC-21

Date: April 28, 2000

Document Effectivity: D6-27370-TBC

Subject: GPWS MINIMUMS VOICE CALLOUT ANOMALY

Reason: To inform flight crews of an anomaly in the DH/MDA voice callout

functionality.

Information in this bulletin is recommended by The Boeing Company, but may not be FAA approved

at the time of writing. In the event of conflict with the FAA approved Airplane Flight Manual (AFM),

the AFM shall supersede. The Boeing Company regards the information or procedures described

herein as having a direct or indirect bearing on the safe operation of this model airplane.

THE FOLLOWING PROCEDURE AND/OR INFORMATION IS EFFECTIVE UPON RECEIPT

Background Information

The DH/MDA Callouts do not always function correctly on airplanes equipped

with Look Ahead Terrain Alerting (GPWS). If the Minimums Reference Selector

(MINS) on the EFIS Control Panel is rotated from BARO to RADIO below 1000

feet AGL, the callout may occur immediately and not at the appropriate altitude.

This does not occur when the switch is rotated above 1000 feet AGL.

The Landing Altitude/Minimums Indications on the PFD display function

correctly. These include the BARO Minimums Pointer and the Minimums

Reference/Altitude.

Operating Instructions

Do not rotate the Minimums Reference Selector (MINS) on the EFIS Control

Panel from BARO to RADIO once the airplane has descended below 1000 feet

AGL.

Administrative Information

Insert this bulletin behind the Operations Manual Bulletin Record page in

Volume 1 of your Operations Manual. Amend the Operations Manual Bulletin

Record to show bulletin TBC-21 “In Effect” (IE).

Page 1 of 2

Sect Name

Section Name

Operations Manual Bulletin

for

The Boeing Company

Seattle, Washington 98124-2207

Number: TBC-22

Date: May 8, 2000

Document Effectivity: D6-27370-TBC

Subject: TCAS DISPLAY ANOMALY

Reason: To inform flight crews of a TCAS display anomaly.

Information in this bulletin is recommended by The Boeing Company, but may not be FAA approved

at the time of writing. In the event of conflict with the FAA approved Airplane Flight Manual (AFM),

the AFM shall supersede. The Boeing Company regards the information or procedures described

herein as having a direct or indirect bearing on the safe operation of this model airplane.

THE FOLLOWING PROCEDURE AND/OR INFORMATION IS EFFECTIVE UPON RECEIPT

Background Information

Flight testing and in-service experience has revealed anomalous TCAS display

behavior for airplanes with TCAS MOPS 7 software installed. The problem is

limited to the relative bearing display of TCAS “other traffic” beyond 40 NM from

the airplane. TCAS “other traffic” is defined as non-threat traffic that is more than

six miles laterally and 1200 feet vertically from the airplane. The following

anomalies have been observed:

• The relative bearing of TCAS “other traffic” targets may be erroneous for

targets beyond the 40 NM range.

• Relative bearing errors of TCAS “other traffic” targets may be as large as

180 degrees and the displayed bearing positions of these targets may change

abruptly.

• Bearing errors for TCAS “other traffic” targets will increase as distance of

traffic from the airplane increases, and are more pronounced at relative

bearings of 360, 90, 180, and 270 degrees.

This problem does not affect relative bearing accuracy of TCAS targets that are

less than 40 NM from the airplane. TCAS alerting and collision avoidance logic

is not affected.

Page 1 of 2

Operations Manual Bulletin No. TBC-22, Dated May 8, 2000 (continued)

Operating Instructions

If a Traffic Advisory (TA) or Resolution Advisory (RA) occurs accomplish the

published Traffic Avoidance procedure. Bearing information for TCAS traffic

targets beyond 40 NM may not be accurate.

Administrative Information

Insert this bulletin behind the Operations Manual Bulletin Record page in

Volume 1 of your Operations Manual. Amend the Operations Manual Bulletin

Record to show bulletin TBC-22 “In Effect” (IE).

This bulletin will be revised to include Service Bulletin information when

available.

CS3-2897

Page 2 of 2

Sect Name

Section Name

Operations Manual Bulletin

for

The Boeing Company

Seattle, Washington 98124-2207

Number: TBC-23

Date: May 17, 2000

Document Effectivity: D6-27370-TBC

Subject: LOOK-AHEAD TERRAIN ALERTING DISPLAY ANOMALIES

Reason: To inform flight crews of display anomalies associated with GPWS look-

ahead terrain alerting.

Information in this bulletin is recommended by The Boeing Company, but may not be FAA approved

at the time of writing. In the event of conflict with the FAA approved Airplane Flight Manual (AFM),

the AFM shall supersede. The Boeing Company regards the information or procedures described

herein as having a direct or indirect bearing on the safe operation of this model airplane.

THE FOLLOWING PROCEDURE AND/OR INFORMATION IS EFFECTIVE UPON RECEIPT

Background Information

During a GPWS look-ahead terrain CAUTION or WARNING, terrain display

data may be positioned inaccurately on the navigation display.

At ranges of 40 NM or greater, solid amber or solid red terrain data displays at an

erroneous distance ahead of the airplane symbol. The error increases as the range

selection is increased and can be up to 20 NM at the 160 NM range setting. Dotted

red, dotted amber, and dotted green terrain data display correctly. Only solid

amber (look-ahead terrain CAUTION active) and solid red terrain (look-ahead

terrain WARNING active) data displays are affected.

In addition, display of solid amber and solid red terrain data may be delayed by 2

or 3 display sweeps after the initial terrain alert. Once displayed, solid terrain data

may be removed on a subsequent display sweep.

Operating Instructions

The terrain data display is intended to serve as a situational awareness tool only.

It does not provide the accuracy or fidelity on which to solely base terrain

avoidance maneuvering decisions.

Page 1 of 2

Operations Manual Bulletin No. TBC-23, Dated May 17, 2000 (continued)

In the event of a look-ahead terrain CAUTION or WARNING, accomplish the

appropriate Terrain Avoidance maneuver in the Non-Normal Maneuvers chapter

of the QRH.

Administrative Information

Insert this bulletin behind the Operations Manual Bulletin Record page in Volume

1 of your Operations Manual. Amend the Operations Manual Bulletin Record to

show bulletin TBC-23 “In Effect” (IE).

This condition is temporary until the system is modified. This bulletin will be

revised to include Service Bulletin information when available.

CS3-2864

Page 2 of 2

Sect Name

Section Name

Operations Manual Bulletin

for

The Boeing Company

Seattle, Washington 98124-2207

Number: TBC-24

Date: May 17, 2000

Document Effectivity: D6-27370-TBC

Subject: GPWS 2500 FOOT VOICE CALLOUT ANOMALY

Reason: To inform flight crews that the 2500 foot radio altitude voice callout may

not occur.

Information in this bulletin is recommended by The Boeing Company, but may not be FAA approved

at the time of writing. In the event of conflict with the FAA approved Airplane Flight Manual (AFM),

the AFM shall supersede. The Boeing Company regards the information or procedures described

herein as having a direct or indirect bearing on the safe operation of this model airplane.

THE FOLLOWING PROCEDURE AND/OR INFORMATION IS EFFECTIVE UPON RECEIPT

Background Information

During an approach over water the GPWS voice callout TWENTY FIVE

HUNDRED may not occur. A recent change to the Collins LRA 900 radio

altimeter introduced an anomaly that may prevent some radio altimeters from

reporting the 2500 foot signal to the GPWS when flying over water due to

temporarily high signal strength conditions.

This bulletin applies to airplanes equipped with faulty Collins LRA 900 radio

altimeters. Operators may also want to apply this bulletin to additional airplanes

equipped with Collins LRA 900 radio altimeters (Part Number 822-0334-002)

with serial numbers prior to 780W.

Collins Service Bulletin No.

3 (LRA 900), dated April 7, 2000, provides

information on the upgrade that corrects this anomaly. It is recommended that

operators contact Collins directly.

Operating Instructions

Do not rely on the voice callout TWENTY FIVE HUNDRED during an approach

over water.

Page 1 of 2

Boeing 737 - 600/700/800/900. Operations Manual (1997 year) - page 5