BULLETIN A53-231

FUSELAGE - Main Frame- Inspect/RepairAft Fuselage Non-Ventral Pressure Bulkhead Tee. This page transmits Revision 2 for DC-9Alert Service BulletinA53-231 to incorporate the following changes: NOTE: This revision constitutesa complete reissue and reflects current operatorsof affected aircraft at time of issue. Reason for Revision:

Page 1: Pages 6

and 7:
Pages 10

and 11:

Pages 12

14, and 15:

February 24/89 To incorporateengineering released subsequent to prior issue of thisAlert Service Bulletin, which adds a different eddy current probe for aircraft which have accomplishedAlert Service Bulletin A53-147. A different eddy currentprobe is required because an operator could not inspect aft pressure bulkhead tee using the standard probe providedby prior issue of this Service Bulletin. This condition is due to the length of Hi-Lok pins used tomodify aircraft per DC-9 Service BulletinA53-147. No additionalwork is required by this revision for aircraft previously inspected/repaired by prior issue of thisAlert Service Bulletin. Changed page number to 1 of 50, was 1of 46. Added NOTE under paragraph 1.C.,Option II, Condition 2. RevisedApproval statement. Changed Service Sketch to 3683D, was 3683C. Added DC-9 Service BulletinA53-147 to References as new paragraph 1.J.(2). Reidentified subsequent paragraphs accordingly. Added paragraphs 1.L and 1.M. Added new GENERAL NOTE 1, reidentified subsequent notes accordingly. Added new paragraph 2.C, reidentified subsequent paragraphs accordingly. Added NOTE under paragraphs2.A.(4) and 2.K.(4).

BulletinA53-231 Page 1 of 2 Revision 2 June 25/93Revised Figure 3 as follows: Added NOTE under paragraph 8.f.(1) on Sheet 2 of 17. Added Note under paragraph B.(1)(a) and revised paragraph (1)(c) under Sequence 1 on Sheet 4 of 17. Revised paragraph (1)(c) under Sequence 2 on Sheet 5 of 17. Added new sheet 7, and 15 through 17. Reidentified sheets accordingly. Revised callout for eddy current probe on Sheet 6 of 17. Revised callout for eddy current probe on Sheet 8 of 17. Revised paragraphs 3.A(1) and 3.A.(3).
Revised paragraphs 3.C.(1) and 3.C.(4).

Revision Seauence: Original Date Revision 1 Revision 2 February 24/89 April 2/90 June 25/93

CAS 

### LL-2

Bulletin A53-231 Page 2 February 24/89 Revision 2 June 25/93 Pages 19

thru 35:

Pages 45

and 46: Pages 47

and 50:BULLETIN A53-231

FUSELAGE- Main Frame - Inspect/RepairAft FuselageNon-Ventral Pressure Bulkhead Tee. QNTE This Alert Service Bulletinis affectedby Federal Aviation AdministrationAirworthinessDirective No. 89-06-04: Amendment 39-6152, effectiveMarch 24, 1989. ThisAlert Service Bulletin is applicableonly to aircraft equipped with the non-ventralaft pressure bulkhead which have accumulated25,000 or more landings. Replacement of all six aft pressure bulkheadtee sections with new improved parts per thisAlert Service Bulletin constitutes closingaction for the repetitive inspection requirementsof thisAlert Service Bulletin. This Alert Service Bulletin supersedesbut does not cancel the requirementsof DC-9 AlertService Bulletin A53-191. Only aircraft listedin thisAlert Service Bulletin that are containedin the Effectivityof Alert Service Bulletin A53-191 are affected by this contingency. ThisAlert Service Bulletin is issuedas a partial record-type change. A service reworkdrawing or aperture cards are furnished in lieu of illustrations. 1. Planning Information: A. Effectivitv: (1) Aircraft Affected: DC-9. Series 10. 30. andC-9

February 24/89 BulletinA53-231 Revision 2 June 25/93 Page 1 of 50(a) Operator and Aircraft Number: Operator Factory Serial No. Operator Factory Serial No. AC 45845 47019 47021 47024 47069 47195 47198 47265 47289 47292 47340 47348 47353 47422 47485 47546 47554 47557 47560 47592 47598 47611 BD .45712 45719 45738 47048 C0 GB and 47022 thru 47071 and and and thru thru thru and 47199 47266 47290 47294 47342 47350 47354

and 45713 and 45739 47423 and EA 45733 45833 45837 45863 47161 47181 47215 47327 47402 and and 47424 45734 45834 

### thru 45865

and 47328

EZ 47220 47355 47414 45728 45874 47040 47074 47147 47165 47269 47384 47403 47413 I1 47408 JP 47392 ML 45835 45838 45866 45869 45876 47140 47157 47166 47186 47214 and 47148

and thru and

and and 45836 45840 45867

47167 47187

NK 47268 NW 45703 45707 45729 45744 45770 45825 45829 47049 47097 47139 47141 47158 47162 47182 47185 47376 thru 45705 and 45708 thru 45749
thru 45832

thru 47145 thru 47164 and 47183

FP 45702

February 24/89 BulletinA53-231 

### Revision 2 June25/93 Page 2ODerator RS

TW

US

VC

XYX

YUZ ZCA

February 24/89 Factory Serial No. 45721 and 45722 45776 45780 and 45781 45783 47125 47127 47082 47095 and 47096 47134 thru 47137 47409 45846 45868 47020 47023 47053 and 47054 47057 and 47058 47066 47068 47188 and 47189 47216 47351 and 47352 45875 47036 47272 47330 and 47331 

### 47399 47401 45696 45711 45718 45725 45727 

### 45795 45842 45720 45714 

### 45736 45743 

### 47043 47059 

### 47085 47122 

### 47126 

## Operator ZCP ZDF

ZGM

ZG4 ZIL
ZJ6 ZK7 ZNV

Z3Z

Z4B Z5F Z5X Z5Y

Z6H Z7B Z8H Factory Serial No. 47151 45871 thru 45873 47270 and 47271 45778 45782 45784 47329 45698 and 45699 47060 

### 45775 45740 47041 47221 47639 45701 45709 45723 

### 45695 47123 47119 45715 and 45716 

### 45735 45737 45741 and 45742 45779 45843 and 45844 47217 45730 45706



### Bulletin A53-231 Page 3 Revision 2 June 25/93(b) Manufacturer's Fuselage and Factory Serial Numbers:

This modification is applicable only to listed aircraft. (2) Spares Affected: None.



### Bulletin A53-231 Page 4 

### February 24/89 Revision 2 June 25/93B. Reason: One operator reported a cracked aft pressure bulkhead attach tee sectionon one aircraft. The aircraftwas a non-ventral bulkhead aircraft. The crack in the upstanding leg of the tee extended circumferentiallyapproximately24 inches from the production end of the tee, at splice between longerons17 and 18 left side, upward to longeron 15. The affected aircrafthad accumulated 36,079 landings when the crack was found. Analysis of the failed part revealed that the crack initiated atmultiple siteson the forward surface of the upstanding leg of the tee as the resultof fatigue due primarily to bending loads. Five other operators reported cracks in a total of eight other aircraft. These eight aircraft had accumulated between 39,172 and 81,915 landings. The predominant areas of cracks were at the upper splice between longeron6 and 7 (4 cases left side); one crack occurred respectively at longeron 8, 11, 12, 13, and 15 (predominately on left side); and lower pylon attach angle at or between longeron 16 and 17 (5 cases left side and one case right side). If cracks are not detected and repaired, they could progress to the point that rapid decompressioncould occur. Inspection of high cycle aircraft and accomplishmentof repairs based on condition will allow continued flight operation. C. DescriDtion: This Service Bulletin accomplishes the following on the fuselage aft pressure bulkhead. Option I (Inspectionfrom aft sideof bulkhead) Performs visual and lowfrequency eddy current inspections for cracked aft pressurebulkhead web-to-fuselagetee sections around the entire periphery of the fuselage from the aft sideof the bulkhead and accomplishes the following: Condition 1 (No Crack) Repetitivelyvisually and low frequencyeddy current inspects for cracks from aft side of bulkhead at intervals specified in Compliance paragraph. Condition 2 (Crack) Replaces cracked tee sectionwith new like or improved part and repetitivelyvisually and low frequencyeddy current inspects for cracks from aft side of bulkheadat intervals specified in Compliance paragraph.

February 24/89 Bulletin A53-231 Page 5 Revision 2 June 25/93Option II (Inspection from forward side of bulkhead) Performs high and low frequency eddy current inspections for cracked aft pressure bulkhead web-to-fuselage tee sections around the entire periphery of the fuselage from the forward side of the bulkhead and accomplishes the following: Condition 1 (No crack) Repetitively high and low frequency eddy current inspects for cracks from forward side of bulkhead at intervals specified in Compliance paragraph. Condition 7 (Crack) Replaces cracked tee section with new like or improved part and repetitively high and low frequency eddy current inspects for cracks from forward side of bulkhead at intervals specified in Compliance paragraph. NOTE: Replacement of all six aft pressure bulkhead tee sections with new improved parts constitutes closing action for the repetitive inspection requirements of this Alert Service Bulletin. D. Compliance: It is recommended that initial inspection/repair of aft pressure bulkhead tee per Option I or II be accomplished as followson aircraft having logged over 25,000 landings. Accumulated Landinas Initial Inspection 25,000 to 49,999 Within 1500 landings from issuedate of Revision 1 of this Service Bulletin 50,000 to 59,999 Within 1000 landings from issuedate of Revision 1 of this Service Bulletin 60,000 and over Within 300 landings from issue date of Revision 1 of this Service Bulletin When aft pressure bulkhead tee section is replaced with new like part, the repetitive inspection for that section of teemay be discontinued until the aircraft has accumulated an additional 25,000 landingsat which time the repetitive Inspection for that section of tee are reinstated along with the ongoing repetitive inspections of the remaining original sections of tee.

BulletinA53-231 February 24/89 Revision 2 June 25/93 Page 6When aft pressure bulkhead tee section Is replaced with new improved part per thisAlert Service Bulletin, the repetitive inspection for that section of teemay be discontinued as this constitutes closing action for that section of tee. Perform the recommendedOption I or Option II repetitive inspections on theremaining original tee sections. Replacement of all sixaft pressure bulkhead tee sectionswith new Improved parts per thisAlert Service Bulletin constitutesclosing action for the inspection requirementsof thisAlert Service Bulletin. It is recommended that repetitive inspection/repairof aft pressure bulkhead tee be accomplished per Option I or II as follows: Option I (Inspection from aft sideof bulkhead) It is recommended that repetitive low frequency eddy current inspection for cracks of side areas above floor between longeronsL7 and L17 on fuselage left and right sides, be accomplishedat intervals not to exceed 2000 landings. It is recommended that repetitive visual inspectionfor cracks of top and lower areas from longeron L7 left sideto longeron L7 right side, and lower fuselage longeron L17 to longeron L20 on fuselage left and right sides, be accomplished at intervals not to exceed 1500 landings. It is recommended that repetitive visual inspectionfor cracksof bottom areas from longeron 120 left side to L20 right side, be accomplished at intervalsnot to exceed 3500 landings. It is recommended that cracked tee section be replaced prior to further pressurized flight. Option II (Inspection from forward sideof bulkhead) It is recommended that repetitive high and low frequency eddy current inspection for cracks around entire peripheryof fuselage from forward side of bulkhead be accomplished at intervalsnot to exceed 2500 landings. It is recommended that cracked tee sectionbe replaced prior to further pressurized flight.
E. Approval: The resultant modification described in paragraph 1.C has been shown to comply with the applicable FederalAviationRegulations and Revision2 is approved by the Manager, LosAngelesAircraft CertificationOffice, FAA Northwest Mountain Region on June 17, 1993, and is approved as an alternatemeans of compliance with paragraphsA, B, and C of Airworthiness Directive No. 89-06-04.

February 24/89 BulletinA53-231 Page 7 Revision 2 June 25/93F. Manpower: NOTE: Man-hours are estimated based on work to be performed by skilled personnel on aircraft/unit which has been placed in a maintenancestatus. Theman-hour/elapsed time estimates do not include: 1. Preparation for themodification: Examples; defueling, purging, placing work stands, opening standard access doors, obtaining tools, and jacking when not essential to the modification. 2. Nonproductive elapsed time: Examples; sealant or adhesive cure time, cleaning, paint drying time, lunch and/or rest periods, and quality assurance inspections. 3. Administrative functions: Examples; planning, engineering liaison, parts requisition, shift change coordination, and report writing. Operators should take the above into consideration when scheduling thismodification.

ODtion I (Inspectionfrom aft side of bulkhead) Optically aided visual inspectionfrom the aft side of the fuselage aft pressure bulkheadmay be accomplished in approximately 22.0man-hours or 11.0 elapsed hours per aircraft. Low frequency eddy current inspection from the aft side of the fuselage aft pressure bulkhead may be accomplished in approximately 11.5 man-hours or 5.8 elapsed hours per aircraft. Man-hours do not include time for fabricationof flexible borescope guide tube. Option II (Inspection from forward side of bulkhead) Removal and reinstallation of lavatories, equipment, and sealant for access to the forward side of the fuselage aft pressure bulkhead teemay be accomplished in approximately 140.1 man-hours or 52.9 elapsed hours per aircraft. High and low frequency eddy current inspection from the forward side of the fuselage aft pressure bulkheadmay be accomplished in approximately 8.0 man-hours or 4.0 elapsed hours per aircraft. Man-hours do not include time for fabricationof eddy current reference standard. Maximum total man-hours and elapsed hours are given for inspection per aircraft. Actual man-hours and elapsed hours for repair are contingent upon inspection findings and are to be estimated by the operator. 

### Bulletin A53-231 February 24/89

Page 8 Revision 2 June 25/93 Page 8G. Material - Cost andAvailability: (1) Aircraft: Parts andmaterials required to accomplish thismodification are listed in paragraph 3.A and are to be procured as indicated. Parts bearing DouglasAircraft Company part numbers are proprietary parts and must be procured under the spare parts article of the purchase agreement, unlessmethods of manufactureare shown. Cost and availabilityof parts are to be negotiated between the operator and DouglasAircraft Company. Reference this Service Bulletin number and direct inquiries to:

(2) Spares: Not applicable. H. Toolina

- Price andAvailability: Option I (Inspectionfrom aft sideof bulkhead) (1) Special test equipment is required to accomplishthe low frequency eddy currentinspection perOption I outlined in this Service Bulletin. Special test equipment is to be procured from operator's stock, or sources indicated in paragraph 3.C. (2) Douglas specialeddy current referencestandard shown in Figure 2 and listed in paragraph 3.C is required to accomplish low frequency eddy current inspectionper Option I andwill bemade available to the operator at no charge. Procurementand availability of SB08530231-9special eddy current reference standard shouldbe negotiated between theoperator and the DouglasAircraft Company. Specify thisService Bulletinnumber and direct inquiriesto: DouglasAircraft Company 910 East 236th Street Carson,California 92805 Attn: Group Leader
- Recovery and ModificationServices 78-22 (DC-9Alert Service BulletinA53-231)



### February 24/89 Bulletin A53-231 Page 9 Revision 2 June 25/93Option II (Inspectionfrom forward side of bulkhead) (3) Test equipment required to accomplish high and low frequency eddy current inspections per Option II is listed in service sketch 3683D. Choice of test equipment is at operator's option and is to be procured from operator's stock or sources indicated in service sketch 3683D. (4) Reference standard required to accomplish high and low frequency eddy current inspections per Option II is shown in service sketch 36830. Reference standardmay be procured from operator's stock, fabricated by the operator, or purchased from source indicated in paragraph 3.D. I. Weight and Balance: Weight change at appropriate fuselage stations by incorporation of any part of thisAlert Service Bulletin is contingent upon the modification of each particular aircraft. Weight data is to be computed by the operator by weighing parts installed and parts removed during modification. Necessary revisions should be made to the appropriate weight and balance document. 3. References: (1) Federal AviationAdministrationAirworthiness Directive No. 89-06-04: Amendment 39-6152, effective March 24, 1989. (2) Alert Service BulletinA53-147. (3) Data used in preparation of thisAlert Service Bulletin: Data Identification DMS 2082 3060157 3060157 MM Chapters 6, 20,

21, 25, 26, 36, 49, 52, and 53 NDT Chapter 1-3 SRM Chapters 51 and 53 SR09530001 SR09530001 SR09530048 SR09530056 SR09530056 SR09530083 5910163 5910163 A B

C D New

C D New

DF DG, DH,

and DJ 3683D 

### Tyoe of Data 

## DouglasMaterial Specification Service ReworkShoring Advance E.O. Maintenance Manual
Nondestructive Testing Manual Structural Repair Manual Service Rework Drawing Advance E.O. Service Rework Drawing Service Rework Drawing Advance E.O. Service Rework Drawing Drawing Advance E.O. Service Sketch (attached)

February 24/89 BulletinA53-231 Revision 2 June 25/93 Page 10(4) Data supplied in supportof this Alert Service Bulletin: Data Identification Change Type of Data J060157 A Service Rework Shoring J060157 B Advance E.O. SR09530001 C Service Rework Drawing SR09530001 D Advance E.O. SR09530048 New Service Rework Drawing SR09530056 C Service Rework Drawing SR09530056 D Advance E.O. SR09530083 New Service Rework Drawing NOTE: Listeddata are being furnished to each affected operator. K. publicationsAffected: Themodificationoutlined in thisAlert Service Bulletinaffects the DC-9 Weight and BalanceDocuments. L. Electrical Load Data: Not affected. M. SoftwareAccomplishmentSummary: Not affected.

February 24/89 Revision 2 June 25/93 

### Bulletin A53-231 Page 112. Accomplishment Instructions: WARNING: TOAVOID INJURY TO MAINTENANCE PERSONNEL OR DAMAGE TO EQUIPMENT,MAKE CERTAIN ADEQUATE PRECAUTIONSARE TAKEN WHILE

- PERFORMINGANY WORK IF ELECTRICALPOWER ISAPPLIED TO THEAIRCRAFT. CAUTION: ELECTRICALLY GROUNDTHE AIRCRAFT. GENERAL NOTES: 

## 1. Replacement ofall six aft pressurebulkheadtee sections with new improved parts constitutesclosing action for the repetitive inspection requirementsof thisAlert Service Bulletin. If replacing all six aft pressure bulkhead tee sections,replacement should be accomplishedone tee section at a time. 2. Refer to sectionsof the MaintenanceManual (MM), Structural Repair Manual (SRM), and Non-Destructive Testing Manual (NDT). 3. Refer to the followingmanual chapters for applicable operations: Manual Chapter Operation MM 20-30-0 SealantApplication NDT 1-3 EddyCurrent Inspection SRM 51-10-4 Drilling and Countersinking SRM 51-30-1 InstallingBolts, Screws, and Washers SRM 51-30-2 Removingand InstallingRivets SRM 51-30-3 Removingand Installing Lockbolts SRM 51-30-5 Removingand InstallingPins SRM 51-60-0 Substitutionand Interchangeability Option I (Inspectionfrom aft sideof bulkhead) A. Operator's Option
- Access doorsmay be Installed in skin on bottom of fuselage forward of auxiliary power unit (APU)door per servicerework drawing SR09530048 to facilitateinspection. B. Operator's Option

- Fabricateguide tube (to be used with flexiscope) from flexible or thinwall tubing to fitoutside diameterof flexiscope as shown on Figure 1. C. Operator's option

- Fabricate reference standardas shown on Figure 2. D. Gain access to inspectionareas on aft side of bulkhead byopening or removing and retainingthe followingaccess doors/panelsas applicable to accomplish visual and/or low frequency eddy current inspection: Access No. AccessArea MM Chapter 5806A Auxiliary Exit Door, 6-12-0 Non-Ventral Bulkhead 5901A Thrust ReverserControl 6-11-4 Valve (Left Side) February 24/89 BulletinA53-231 Page 12 Revision 2 June 25/93AccessArea MM Chapter 5902A Thrust Reverser Control 6-11-4 Valve (RightSide) 5903A APU Service (Left Side) 6-11-4 5904A APU Service (Right Side) 6-11-4 

### NoTE:The following paragraphs 2.D through 2.H may be accomplished at operator's option and are applicable to visual inspection requirements. E. Remove and retainAPU and attaching parts. (See MM chapter 49-10-0, paragraph entitled "Removal/InstallationPower Plant.") F. Remove and retainAPU compartment enclosure and attaching parts. (See MM chapter 53-20-5, paragraph entitled "Removal/Installation APU Compartment Enclosure.") G. Remove and retain lower firex bottle and attaching parts. (See MM chapter 26-20-1, paragraph entitled, "Removal/Installation Fire ExtinguishingContainers.") H. Remove and retain right pneumatic crossfeed valve pushrod and attaching parts. (See MM chapter 36-10-3, paragraph entitled "Removal/Installation Pneumatic CrossfeedValve.") I. Remove and retain two upper 5953635 conditioned air duct assemblies, check valves, and attaching parts aft of pressure bulkhead center ceiling. (See MM chapter 21-20-2, paragraph entitled "Removal/Installation Conditioned and Cold Air Check Valve.") J. Roll back or remove and retain Insulation blankets from aft side of aft pressure bulkhead. (See MM chapter 25-22-0, paragraph entitled "Removal/Installation InsulationBlankets.") K. Perform optically aided visual and low frequency eddy current inspection/repair of the aft pressure bulkhead web to fuselage skin attach tee sections from the aft side of the bulkhead as follows: (1) Inspect the upstanding leg of 5910163 non-ventral bulkhead tee sections from aft side of bulkhead around the periphery of the bulkhead as shown on Figure 3 and accomplish the following: Condition 1 (No Crack) (2) Perform repetitive visual and/or low frequency eddy current inspections from aft side of bulkhead at intervals specified in Compliance paragraph.

BulletinA53-231 February 24/89 2 Access No.



### Revision 2 June 25/93 Page 13Condition 2 (Crack) (3) Replace crackedtee section with new like or improved part per Figure4 (See Table I for configuration) prior to further pressurized flight. Perform repetitive visual and/or low frequency eddy current inspections from aft side of bulkhead at intervals specified in Compliance paragraph. (4) If any tee section is to be replaced, remove and retain engines 1 and 2. (SeeMM chapter 71-00-0, paragraph entitled "Removal/InstallationPower Plant.") NOTE: If replacing all six aft pressure bulkhead tee sections,replacement should be accomplished one tee section at a time. (5) Shore aircraft as shownon Figure 5. L. Record and report all results negative and positive of inspectionto DAC. Include fuselage number, factory serial number, crack location, crack length, flight-hours,and accumulated landingsof aircraft. Forward to: DouglasAircraft Company P.O. Box 1771 Long Beach, California 90801 Attn: Manager, Customer Service 76-40 (DC-9Alert Service BulletinA53-231) M. Apply PR-1422 B-2 sealant around entire periphery of the bulkhead tee sections,as applicable. N. Reinstall retained insulation blankets on aft side of aft pressure bulkhead. (See MM chapter 25-22-0, paragraph entitled, "Removal/InstallationInsulation Blankets.") 0. Reinstall right pneumatic crossfeed valve pushrod and attaching parts as applicable. (See MM chapter 36-10-3, paragraph entitled "Removal/InstallationPneumaticCrossfeed Valve.") P. Reinstall two upper 5953635 conditioned air duct assemblies, check valves, and attaching parts as applicable. (SeeMM chapter 21-20-2, paragraph entitled "Removal/InstallationConditioned and ColdAir CheckValve.") Q. Reinstall lower firex bottle and attaching parts as applicable. (See MM chapter 26-20-1, paragraph entitled, "Removal/Installation Fire ExtinguishingContainers.") R. ReinstallAPU compartmentenclosure, as applicable. (SeeMM chapter 53-20-5. paragraph entitled "removal/InstallationAPU Compartment Enclosure.") February 24/89 BulletinA53-231 Page 14 

### Revision 2 June25/93S. ReinstallAPU and attaching parts as applicable. (See MM chapter 49-10-0, paragraph entitled "Removal/InstallationPower Plant.") T. Reinstall engines 1 and 2 as applicable. (SeeMM chapter 71-00-0, paragraph entitled "Removal/InstallationPower Plant.") U. Remove shoring as shown on Figure 5 as applicable. V. Close/reinstall access doors/panels as outlined under Option I paragraph 2.C. ODtion II (Inspection from forward sideof bulkhead) A. Perform high and low frequency eddy current inspections of the aft pressure bulkhead web to fuselage skin attach tee sections from the forward side of the bulkhead as follows: (1) Operator's Option

- Fabricate eddy current reference standard as shown on service sketch 3683D, Figure 5. (2) Remove and retain items as outlined in service sketch 3683D, Table I, as applicable. (3) Inspect the standing leg of 5910163 or SB09530056 non-ventral bulkhead tee sections from forward sideof bulkhead around the entire periphery of the bulkhead as shownon service sketch 3683D, and accomplish the following: Condition 1 (No Crack) Perform repetitive high and low frequency eddy current inspections from forward side of bulkhead at intervalsspecified in Compliance paragraph. Condition 2 (Crack) Replace cracked tee section with new like or improved part per Figure 4 (See Table I for configuration)prior to further pressurized flight. Perform repetitivehigh and low frequency eddy current inspections from forward side of bulkhead at intervals specified in Compliance paragraph. (4) If any tee section is to be replaced,remove and retain engines 1 and 2. (SeeMM chapter 71-00-0, paragraph entitled "Removal/Installation Power Plant.") Shore aircraft as shown on Figure 5. NOTE: If replacing all six aft pressure bulkhead tee sections, replacement should be accomplished one tee section at a time.



### Bulletin A53-231 February 24/89 Revision 2 June 25/93 Page 15B. Record and report all results negativeand positive of inspection to DAC. Include fuselage number, factory serial number, crack location, crack length, flight-hours, and accumulated landings of aircraft. Forward to:

C. Apply PR-1422 B-2 sealant around entireperiphery of the bulkhead tee sections, as applicable. D. Reinstall engines 1 and 2 as applicable. (See MM chapter71-00-0, paragraph entitled "Removal/InstallationPower Plant.")
E. Remove shoring as shown on Figure 5 as applicable. F. Close/reinstall retained items as outlined in service sketch 3683D Table I, as applicable.

February 24/89 BulletinA53-231 Revision 2 June 25/93 Page 16BulletinA53-2 Page 17 FLEXIBLE BORESCOPE GUIDE TUBE - FABRICATIONAND USE 31 FIGURE 1 

### Rev i February 24/89

sion 2 June 25/93EDDY CURRENT REFERENCESTANDARD - FABRICATION February 24/89 FIGURE 2 Revision 2 June 25/93 BulletinA53-231 Page 18

### Bulletin A53-231 Page 19 AFT PRESSURE BULKHEAD TEE - INSPECTION FIGURE 3 (SHEET 1 OF 17) February 24/89 Revision 2 June 25/93February 24/89 Revision 2 June 25/93 AFT PRESSURE BULKHEAD TEE - INSPECTION FIGURE 3 (SHEET 2 OF 17) Bulletin A53-231 Page 20

## *Bulletin A53-231 Page 21 AFT PRESSURE BULKHEAD TEE - INSPECTION FIGURE 3 (SHEET 3 OF 17) February 24/89 Revision 2 June 25/93AFT PRESSURE BULKHEADTEE - INSPECTION February 24/89 FIGURE 3 (SHEET4 OF 17) 

### Revision 2June 25/93 

### Bulletin A53-231 Page 22Bulletin A53-231 Page 23 AFT PRESSURE BULKHEAD TEE - INSPECTION FIGURE 3 (SHEET 5 OF 17) February 24/89 Revision 2 June 25/93AFT PRESSURE BULKHEADTEE - INSPECTION February 24/89 FIGURE 3 (SHEET 6 OF 17) Revision 2 June 25/93 Bulletin A53-231 Page 24Bulletin A53-231 Page 25 AFT PRESSURE BULKHEAD TEE - INSPECTION FIGURE 3 (SHEET 7 OF 17) February 24/89 Revision 2 June 25/93

### February 24/89 AFT PRESSURE BULKHEAD TEE - INSPECTION FIGURE 3 (SHEET 8 OF 17) Revision 2 June 25/93 BulletinA53-231 Page 26BulletinA53-231 Page 27 AFT PRESSURE BULKHEAD TEE - INSPECTION FIGURE3 (SHEET9 OF 17) February 24/89 Revision 2 June 25/93February 24/89 AFT PRESSURE BULKHEAD TEE - INSPECTION FIGURE 3 (SHEET 10 OF 17) Revision 2 June 25/93 Bulletin A53-231 Page 28

## Bulletin A53-231 Page 29 AFT PRESSURE BULKHEAD TEE - INSPECTION FIGURE 3 (SHEET 11 OF 17) 

### February 24/89 Revision 2 June 25/93February 24/89 Revision 2 June 25/93 AFT PRESSUREBULKHEAD TEE - INSPECTION FIGURE 3 (SHEET 12 OF 17) BulletinA53-231 Page 30BulletinA53-231 Page 31 AFT PRESSURE BULKHEAD TEE - INSPECTION FIGURE 3 (SHEET 13 OF 17) February 24/89 Revision 2 June 25/93AFT PRESSURE BULKHEAD TEE - INSPECTION February 24/89 FIGURE 3 (SHEET 14 OF 17) 

### Revision 2June 25/93 

### Bulletin A53-231 Page 32BulletinA53-231 Page 33 AFT PRESSURE BULKHEAD TEE - INSPECTION FIGURE 3 (SHEET 15 OF 17) February 24/89 Revision 2 June 25/93AFT PRESSURE BULKHEADTEE - INSPECTION February 24/89 FIGURE 3 (SHEET16 OF 17) Revision 2 June 25/93 BulletinA53-231 Page 34BulletinA53-231 Page 35 AFT PRESSURE BULKHEAD TEE - INSPECTION FIGURE 3 (SHEET 17 OF 17) February 24/89 Revision 2 June 25/93AFT PRESSURE BULKHEADTEE - INSPECTION February 24/89 FIGURE 4 (SHEET 1 OF 6) Revision 2 June 25/93 

### Bulletin A53-231 Page 36BulletinA53-231 Page 37 AFT PRESSURE BULKHEAD TEE - INSPECTION FIGURE 4 (SHEET 2 OF 6) February 24/89 Revision 2 June 25/93AFT PRESSUREBULKHEAD TEE - INSPECTION February 24/89 FIGURE 4 (SHEET 3 OF 6) Revision 2 June 25/93 BulletinA53-231 Page 38BulletinA53-231 Page 39 AFT PRESSURE BULKHEAD TEE - INSPECTION FIGURE 4 (SHEET4 OF 6) February 24/89 Revision 2 June 25/93AFT PRESSURE BULKHEAD TEE - INSPECTION February 24/89 FIGURE 4 (SHEET 5 OF 6) Revision 2 June 25/93 

### Bulletin A53-231 Page 40Bulletin A53-231 Page 41 AFT PRESSURE BULKHEAD TEE - INSPECTION FIGURE 4 (SHEET 6 OF 6) February 24/89 Revision 2 June 25/93SHORING INSTRUCTIONS- NON-VENTRALAFT PRESSURE BULKHEAD TEE REPLACEMENT February 24/89 FIGURE 5 (SHEET 1OF 3) Bulletin A53-231 

### Revision 2 June 25/93 Page 42SHORING INSTRUCTIONS - NON-VENTRAL AFT PRESSUREBULKHEAD TEE REPLACEMENT FIGURE 5 (SHEET 2 OF 3) February 24/8! Revision 2 June 25/93 e n Page 43 nSHORING INSTRUCTIONS- NON-VENTRALAFT PRESSURE BULKHEAD TEE REPLACEMENT February 24/89 FIGURE 5 (SHEET 3 OF 3) Bulletin A53-231 Revision 2 June 25/93 Page 44February 24/89 Revision 2 June 25/93 

### Bulletin A53-231 Page 45BulletinA53-231 Page 46 February24/89 Revision 2 June 25/93B. The basis for the followinamaterial data is per spares. None. C. The basis for the following toolina data is per operator. (1) Option I - Test equipment to be procured from operator's stock or sources indicated. NOTE: One 70 or 90 degree endoscope of any diameter with 18 inch minimum length andmatching light sourcemay be used. 

### Test Equipment Supplier Endoscope 70 Degree

(Foreoblique)Angle 19 (304.8MM)-Inch Long 0.217 (5.51 MM)-Inch Diameter 

## or Equivalent Fiber Optic

Light Bundle and Endoscope Light Source

110 or 220Volt and Sylvania Projector Lamp

150 Watt, 120Volt Model 103200

Model

1F8D3 1 54341 Expanded Optics, Incorporated 301-C West Dyer Road SantaAna, California 92702-3427

1

No. 00482 or No. E0590 1 

### QNTE:Similar or equivalent endoscopes and illuminatorsmay be obtained from the following sources.

BulletinA53-231 February 24/89 Page 47 Revision 2 June 25/93BulletinA53-231 Page 48 February 24/89 Revision 2 June 25/93

### TIY Otv AE Supplier Eddy Current Low

Frequency Molded Probe 5-50 kHz Operating Frequency Model 1 C/N 935-0120 P/N APB/MSP (Zetec Incorporated)

or Eddy Current Low

Frequency Molded Probe 5-50 kHz Operating Frequency Model SP0-4080 (StaveleyInstruments Incorporated)

Eddy Current Low

Frequency 90 Degree Probe 5-50 kHz Operating Frequency Model 1 C/N 910-5830 P/NAPB/90DP (Zetec Incorporated)

or Eddy Current Low

Frequency 90 Degree Probe 5-50 kHz Operating Frequency
or Eddy Current Low

Frequency 90 Degree Probe 5-50 kHz Operating Frequency Model SPO-4081 (StaveleyInstruments Incorporated)

Model SP0-5222

NOTE: When ordering Eddy Current probes specify type of Eddy Current instrumentthe probe will be used with so that propermating connectors or adapter will be provided. (2) Option I - One SB09530231-9Eddy Current ReferenceStandard required to accomplish Option I low frequencyeddy current inspectionwill be made available at no charge. (See paragraph 1.H.) (3) Option II

- Test equipmentrequired to accomplish Option II high and low frequency eddy current inspections includingprocurement sources, is listed in service sketch 3683D. Choice of equipment is at operator's option and is to be procured from operator's stockor sources indicated in service sketch 3683D.

February 24/89 BulletinA53-231 Revision 2 June 25/93 Page 49 

### Test Equipment(4) Option II

- The following reference standard required to accomplish the Option II high and low frequencyeddy current inspections Is to be procured from operator's stockor as indicated.InstructionsPart No. Qtv Kev Word Disposition MS20470AD5-6 2 Rivet 2/ 2/ MS20470AD5-7 4 Rivet Z/ I/ SB09530231-11 1 Plate I/ 4/ SB09530231-13 1 Web I/ 5/ SB09530231-15 1 Tee 1/ 6/ SB09530231-17 1 Reference 1/ StandardAssy 1/ May be purchased from: VM Products Incorporated E 11298 62nd Avenue 60761 Puyallup, Washington 98373 or May be fabricated by the operator. (See service sketch 3683D.) 2/ May be procured from operator's stock. 2/ Detail of SB09530231-17 reference standard assembly. 4/ May be fabricated by the operator from 7075-T6 clad aluminum sheet Material Specification QQ-A-250/13 Temper T6 or 7075-T6 bare aluminum plate Material Specification QQ-A-250/12 Temper T6, .047/.053 x 2-1/4 x 3 Inches. (See service sketch 3683D.) 5/ May be fabricated by the operator from 7075-T6 clad aluminum sheet Material SpecificationQQ-A-250/13 Temper T6 or 7075-T6 bare aluminum plate Material Specification QQ-A-250/12 Temper T6, .039/.045 x 2-1/4 x 4-1/2 Inches. (See service sketch 36830.) I/ May be fabricated by the operator from 2024-T3 clad aluminum sheet Material Specification QQ-A-250/5 Temper T3 or 2024-T4 bare aluminum plate Material Specification QQ-A-250/4 Temper T4, .075/.085 x 3 x 4-1/2 Inches. (See service sketch 3683D.) Any Inquiries regarding accuracy, timeliness, completeness, and legibility of this Alert Service Bulletin should be directed to the local DAC Field Representative, or: DouglasAircraft Company P.O. Box 1771 Long Beach, California 90801 Attn: Business Unit Manager Service Bulletins Service Changes and Modification Kits Product Support 76-40 (DC-9Alert Service Bulletin A53-231) ENW/CAS G3H/LL BulletinA53-231 February 24/89 Revision 2 June 25/93 Page 50INSPECTIONPROCEDURE 1. GENERAL NOTES: (1) This procedure describes high and low frequency Eddy Current inspectionof DC-9 aft pressure bulkhead tee sections to detect fatigue cracks in standing legof tee sections. (2) Inspection for cracks bulkhead. of either ventral or nonventral bulkhead tee sections ismade from the forward side of the aft pressure (See Figures 1 and 2.) 2. TEST EqUIPMENT: A. EddyCurrent Equipment: (1) Eddy Current CRT Instruments: Nortec NDT-15, NTD-18, or NDT-19

or Zetec EM3300, or EM4300

or HockingAeromaster G, AVIOB orAV100

## or Hocking Electronics Limited St.Albans, Hertfordshire England Equivalent NOTE: Eddy current Instruments with meters are not acceptable for this Inspection. (2) High Frequency Eddy Current Probes. (SeeFigure 4.) Shielded pencil/surface (90' angle) operating at about 200 kHz, 0.125-Inchmaximum diameter. Model MP901-60B 90'Angle NDT Products Engineering or 7056 South 220 Street Model MP901-60FX 90'Angle Kent, Washington 98032

or Model 1R90F-6-1/16 J



## or CAGE: 61100 

## GKEngineering Corporation 21610 Lassen Street Suite 1 

## Chatsworth, California 91311-4121 CAGE: 58136 Equivalent. N0TE: When ordering Eddy Current probes specify type of Eddy Current Instrument the probe will be used with so that proper mating connectors or adapter will be provided. (3) Low Frequency Eddy Current Probe. (See Figure 4.) Right angle, 1/2-inch drop, surface probeoperating at 1-40 kHz. Model SPO 1071 Staveley Instruments Incorporated 421 North Quay Street Kennewick,Washington 99336-7735 or CAGE: 29192 

## Equivalent (4) Eddy Current Reference Standard
- LocalManufacture. (See Figure5.) N0TE: May be purchased from: VM Products Incorporated 1129862ndAvenue Puyallup, Washington 98373 CAGE: 607613. ACCESS PREPARATIONFOR INSPECTION:

a. Gain access to work area by removing and retaining items outlined in Table I, as applicable. Access below the FRP isthrough cargo compartment access panels. (See Figure 3.) b. Remove and retain,or loosen wire bundles, ducting,hydraulic lines, and attaching parts, as required.
c. Remove sealantfrom inspectionarea and clean with lint-freewiper and 1,1,1 trichloroethanesolvent or equivalent.

TABLE I

REMOVEAND RETAIN MM CHAPTER REFERENCE PARAGRAPHTITLE AFT LAVATORYEQUIPMENT,TOILET WASTE TANKS, WASTE PLUMBING AND LAVATORY(IES),PARTITIONS AND/ORAFT GALLEY(IES),AND ATTACHING PARTSASAPPLICABLE IMMEDIATELYFORWARDOFAFT PRESSURE BULKHEAD. CARPETINGAND FLOORPANELS, LAVATORY FLOOR PANSAND/OR GALLEY FLOOR PANELS,AND ATTACHING PARTSASAPPLICABLE, IMMEDIATELYFORWARDOFAFT PRESSURE BULKHEAD. 25-30-0 THRU 25-41-0 REMOVALS/INSTALLATION (ASAPPLICABLE.)

38-30-1 AND/OR 53-20-3 25-20-0 AND/OR 53-20-7 GENERAL,AND REMOVAL/INSTALLATION GALLEYFLOOR COVERING.

INSULATIONBLANKETSAND ATTACHING PARTS ON FORWARD SIDE OFAFT PRESSUREBULKHEAD AS NECESSARYTO GAINACCESS TO INSPECTIONAREA. THRUST REVERSERCONTROLVALVE SECTORAND BRACKET. APPLICABLE TO DC-9 SERIES MD-80 AIRCRAFTONLY - CABIN AIR RECIRCULATIONFAN. 25-22-0 AND 25-52-1

78-31-2 REMOVAL/INSTALLATIONINSULATION BLANKETSAND REMOVAL/INSTALLATION SIDEWALL,CEILING,AND FLOOR PANELS. REMOVAL/INSTALLATIONTHRUST REVERSERCONTROLVALVE SECTOR. 21-20-13 REMOVAL/INSTALLATIONCABIN AIR RECIRCULATION FAN.4. HIGH FREQUENCY PROCEDURE: NOTE: High frequency procedure is applicable to Eddy Current inspectionin area of tee sectionsnot covered by the bulkhead web. A. Connect high frequency Eddy Current probe and set frequency at approximately200 kilohertz. Place probe on referencestandardand balanceinstrument permanufacturer's instructions. (SeeFigure6.) B. Set sensitivityand phase controls to obtain CRT responsefrom notch 5. Without changing sensitivity, scan notches 5 and 6 and observe CRT presentation of crack. (See Figures 6 and 7.) C. Place probe on tee and slowly scan surface towardand away fromthe vertex of tee angle. Do not adjust balance, phase, or sensitivitycontrols. With the exception of tee splice plate areas,progressivelyscan entire 360 degrees of tee sections forward perimeter. (SeeFigure 8.) NOTE: One technician is to operate the probe while another technician evaluatesthe Eddy Current response on the CRT. Technician watching CRT should periodicallyerase the lift-offtraces from the scopeto avoid missing a small crack indication as shown in Figure 9 views (a) and (b). Technician watching scopemust continuallytalk to technician operating probe to indicate if probe ismaking good contact withmetal surface as illustrated in View (c). D. Any indicationwhich exhibits same relativephase angle and an amplitude equal to or greater than 50 percent of CRT presentation obtained from calibrationnotch 6 in the reference standardis considereda crack. E. Measure length of each crack and distance betweenmultiple cracks. Report all crack indicationsto DAC as noted. 5. LOW FREQUENCYPROCEDURE: NOTE: Low frequency procedure is applicable to Eddy Current inspection of tee sectionscovered by the bulkhead web. F. Connectlow frequencyEddy Current probe and set frequencyat approximatelyfive kilohertz. Place probe on referencestandardat probe position A and scan notches 2 and 4 and observe CRT presentation of crack. (See Figure 10.)

DC-9 S/BA53-191,A53-231, 

### REF: AND A53-232 SERVICESKETCH SHEET 3683D OF NO. 

### 19G. Set sensitivityand phase controlsto obtain CRT responsefrom notches 2 and 4 as shown on Figure 11 (a). H. Without changing sensitivityplace probe on web and scanaround each fastener inthe splice plate area paying particular attentionto area near edge of web. Progressivelyscanentire 360 degreesof tee sections splice plate areas forward perimeter. (See Figure 12.) NOTE: One technician is to operatethe probe while another technicianevaluatesthe Eddy Current responseon the CRT. Technician watching CRT should periodicallyerase the lift-offtraces from the scope to avoid missing a small crack indication as shown in Figure 9, Views (a) and (b). Technician watching scopemust continuallytalk to technicianoperating probeto indicateif probe is making good contact with metal surface as illustrated in View (c). I. Recalibrate instrument at two kilohertz with probe at position B on reference standard. Scan across notches 1 and 3. Set sensitivity and phase controls to obtain CRT response from notches 1 and 3 as shown on Figure 11 (b). Without changing sensitivity,place probe on tee splice plate area and scan around fasteners payingparticular attentionto area near edge of splice plate. (SeeFigure 12.) J. Any indicationwhich exhibitsthe same relativephase angleand an amplitude equal to or greaterthan 50 percentof CRT presentation obtained from the half thickness notches 3 and 4 in reference standard is considered a crack. Cracks may be confirmed by checking the aft side of the tee using the high frequency procedure in paragraphsA through E. Cracks which do not breakthrough to the aft surfaceof the teemay be checked using this low frequency procedureof paragraphsF through K. K. Measure lengthof each crack and distance betweenmultiple cracks. Report all crack indications to DAC as noted.

DC-9 S/BA53-191,A53-231, REF: ANDA53-232 SERVICESKETCH SHEET 5 3683D OF 19 NO.DC-9 S/B A53-191, A53-231, REF: ANDA53-232

SERVICE SKETCH SHEET 6 NO. 3683D OF 19FIGURE 2. DC-9 NON-VENTRAL AFT PRESSUREBULKHEAD. TYPICAL FOR VENTRAL AFT PRESSURE BULKHEAD. DC-9 S/B A53-191, A53-231, REF: ANDA53-232

SERVICE SKETCH SHEET 7 NO. 3683D OF 19ACCESS PANEL LOCATION AFT END OF CARGO COMPARTMENT (LOOKINGAFT)

FIGURE 3.

DC-9 S/B A53-191, A53-231, REF: ANDA53-232

SERVICE SKETCH 

## NO. 3683D SHEET 8 OF 

### 19GK ENGINEERING 1R90F-6-1/16J
FIGURE 4. EDDY CURRENT PROBES DC-9 S/B A53-191, A53-231, REF: ANDA53-232

SERVICE SKETCH SHEET 9 NO. 3683D OF 19DC-9 S/B A53-191, A53-231, REF: ANDA53-232

SERVICE SKETCH SHEET 10 NO. 3683D OF 19DETAIL SB09530231-15TEE FABRICATEFROM 2024-T3 CLADALUMINUM SHEET MATERIALSPECIFICATIONQQ-A-250/5 TEMPER T3 OR 2024-T4 BAREALUMINUM PLATE MATERIAL SPECIFICATIONQQ-A-250/4TEMPER T4, .075/.085 X 3 X 4-1/2 INCHES

HIGHAND LOW FREQUENCY EDDY CURRENT REFERENCESTANDARD - FABRICATION



### DC-9 S/B A53-191, A53-231, REF: ANDA53-232 SERVICE SKETCH NO. 3683D SHEET 11 OF 19 FIGURE 5.DETAIL SB09530231-11PLATE FABRICATE FROM 7075-T6 CLADALUMINUMSHEET MATERIAL SPECIFICATIONQQ-A-250/13TEMPER T6 OR 7075-T6 BAREALUMINUM PLATEMATERIAL SPECIFICATION QQ-A-250/12TEMPERT6 .047/.053 X 2-1/4 X 3 INCHES HIGHAND LOW FREQUENCYEDDY CURRENT REFERENCESTANDARD - FABRICATION (CONT)DC-9 S/B A53-191, A53-231, REF: ANDA53-232

SERVICE SKETCH NO. 3683D 

### SHEET 12 OF 19 FIGURE 5.REFERENCE STANDARDMAY BE PURCHASEDFROM: VM PRODUCTS INCORPORATED 11029 POLK STREET EAST P. O. BOX 44926 TACOMA, WASHINGTON 98444 CAGE: 60761

FIGURE 5.

- HIGHAD LOW FREQUENCYEDDY CURRENT REFERENCE STANDARD- FABRICATION (CONT)

DC-9 S/BA53-191, A53-231, REF: ANDA53-232

SERVICE SKETCH 

### SHEET 13 19 3683D OF NO.FIGURE 7. SCOPE PRESENTATION 

### DC-9 S/B A53-191, A53-231, REF: AND A53-232 SERVICE SKETCH SHEET 14 NO. 3683D OF 19FIGURE 8. EDDY CURRENTCHECK OF BULKHEAD TEE (360 ° ) FROM FORWARD SIDE

DC-9 S/BA53-191, A53-231, REF: ANDA53-232

SERVICE SKETCH SHEET 15 NO. 3683D OF 19FIGURE 9. CRT PRESENTATIONS USING PROBE DC-9 S/BA53-191,A53-231, REF: ANDA53-232

SERVICE SKETCH SHEET 16 NO. 3683D OF 19FIGURE 10. LOW FREQUENCYCALIBRATION PROCEDUREUSINGNOTCHES 1THROUGH 4

DC-9 S/BA53-191,A53-231, REF: ANDA53-232

SERVICE SKETCH NO. 3683D SHEET 17 OF 19

### DC-9S/B A53-191, A53-231, REF: AND A53-232 SERVICE SKETCH SHEET 18 NO. 3683D OF 19FIGURE 12. LOW FREQUENCY EDDYCURRENT CHECK OF BULKHEADTEE (360°) THROUGHWEB AND SPLICEPLATES

DC-9 S/BA53-191, A53-231, REF: AND A53-232 SERVICE SKETCH SHEET 19 3683D OF 19 NO.