THIS MATERIAL CONTAINS PROPRIETARY INFORMATION OF LOCKHEED MARTIN AERONAUTICAL SYSTEMS. DISCLOSURE TO OTHERS, USE OR COPYING 

WITHOUT EXPRESS WRITTEN AUTHORIZATION OF LOCKHEED MARTIN AERONAUTICAL SYSTEMS IS STRICTLY PROHIBITED.

© 2013 LOCKHEED MARTIN CORPORATION. UNPUBLISHED WORK. ALL RIGHTS RESERVED.

May 31, 2013 093-53-105

FUSELAGE -

AFT PRESSURE BULKHEAD - STRINGER END FITTING

INSPECTIONS AND REQUIRED MODIFICATION

REVISION TRANSMITTAL SHEET

This sheet transmits Revision 3 to Service Bulletin 093-53-105.

This Revision is issued to:

 Change the inspection requirements for all aircraft and add a stringer end fitting modification 

requirement. These changes resulted from compliance with the 14 CFR Part 26 – Subpart C –

Aging Airplane Safety – Widespread Fatigue Damage rule.

 Added paragraph 1.C. SAFETY INTENT

 Added paragraphs 2.E. and 2.F.

The inspections of Service Bulletin 093-53-105, Revision 1 were mandated by AD 95-26-11.

This revision is a complete reissue. Revised information is indicated by a vertical bar in the right

margin.

Further work is required on aircraft inspected by previous issues of this service bulletin. This further 

work consists of continuation of the inspections at a different repeat interval and a required time 

compliance modification as stated in Paragraph 1. B. REASON.

The EFFECTIVITY information in Section 1, Paragraph A.(1), and the technical content of the 

ACCOMPLISHMENT INSTRUCTIONS in Section 2 of this service bulletin are FAA approved.

LIST OF PREVIOUS REVISIONS AND/OR REISSUES

Basic Issue, April 1, 1992

Revision 1, November 17, 1995 (Reissue)

Revision 2, August 6, 1996 (Reissue)
THIS MATERIAL CONTAINS PROPRIETARY INFORMATION OF LOCKHEED MARTIN AERONAUTICAL SYSTEMS. DISCLOSURE TO OTHERS, USE OR COPYING 

WITHOUT EXPRESS WRITTEN AUTHORIZATION OF LOCKHEED MARTIN AERONAUTICAL SYSTEMS IS STRICTLY PROHIBITED.

© 2013 LOCKHEED MARTIN CORPORATION. UNPUBLISHED WORK. ALL RIGHTS RESERVED.

April 1, 1992 093-53-105

Rev. 3, May 15, 2013 Page 1 of 31

FUSELAGE -

AFT PRESSURE BULKHEAD - STRINGER END FITTING

INSPECTIONS AND REQUIRED MODIFICATION

1. PLANNING INFORMATION

A. EFFECTIVITY

NOTE: This service bulletin is applicable to the following L-1011 aircraft models:

L-1011-385-1

L-1011-385-1-14

L-1011-385-1-15

L-1011-385-3

(1) Aircraft Affected

Lockheed Martin Serial No. 193A through Y; 293A through F: -1002 through -1250.

(2) Aircraft Ownership and Registration

Service Bulletin 093-11-126 lists L-1011 aircraft which have been sold by the original 

operator and provides information on current ownership and registration numbers for 

those aircraft. The bulletin also lists model and current registration numbers for all 

existing aircraft.

(3) Spares Affected

There are no Lockheed Martin supplied spares for this modification.

B. REASON

During the final stages of the L-1011 aircraft fatigue test program, cracks were discovered in 

ten fittings at stringer attachments to the upper region of the aft pressure bulkhead.

On August 24, 1995, an L-1011 aircraft was three hours into a transoceanic flight when it 

experienced a rapid decompression. After the aircraft safely returned to its point of 

departure, an inspection revealed twenty (20) stringer end fittings severed (stringer 55 to 64 

and stringer 1 to 10) and approximately a twelve (12) foot circumferential crack at the twelve 

o'clock position in the vertical leg of the 1503620-103, -109 and -111 tee caps. These tee caps 

splice the periphery of the aft pressure dome to the aft pressure bulkhead frame, stringer end 

fittings, and fuselage skin. The aircraft had accumulated 25,721 flight cycles at the time of 

the incident. 
April 1, 1992 093-53-105

Rev. 3, May 31, 2013 Page 2

After the basic issue of this service bulletin, some operators reported finding stringer end 

fittings cracked using an ECSS inspection which had been previously reported without cracks 

using a visual inspection. Therefore, if an operator's previous inspections were visual, then 

an ECSS inspection was added to be accomplished within thirty (30) days after receipt of 

Revision 1 of this service bulletin.

Revision 1 permitted the operator to defer the ECSS inspection to a maximum of 90 days by 

performing a visual inspection within 30 days after receipt of Revision 1 of this service bulletin 

and repeat the visual inspection every 50 flight cycles. This deviation was included in the

FAA Airworthiness Directive 95-26-11, Paragraph (f) which became effective on January 11, 

1996 and superseded AD 95-18-52 which was issued on September 6, 1995.

Revision 1 also deleted all information pertaining to the R4/L4 Door Stop Intercostals and 

revised the title and the aircraft serial numbers. (Door stop intercostal information is now 

included in Service Bulletin 093-53-270.) Revision 1 expanded the inspection to stringer 1 

through 14 and 52 through 64 (AD 95-18-52 required stringer 1 through 10 and 56 through 

64). The area of inspection was expanded as part of an overall plan to assure inspection of all 

bulkhead tension fittings through various service bulletins.

Revision 2 revised the inspection requirements at stringer locations 12, 13, 53, and 54 for 

aircraft with a large (47" wide) aft passenger door (Serial No. 193G, H, J, K, N, V, W, Y and 

293A, B, C, and F). These locations could not be ECSS inspected per the service bulletin 

because of an inaccessibility problem caused by the door counterbalance, track guide and all 

the structure which supports these items. This obstruction was verified by Lockheed Martin 

Engineering and the end fitting ECSS inspection was changed in Revision 2 to an optical 

inspection with an additional ECSS inspection of the skin at the four (4) stringer locations for 

the sixty-nine (69) aircraft with the large aft passenger door.

On January 14, 2011, the Widespread Fatigue Damage rule of 14 CFR Part 26 became 

effective. In compliance with this rule, Lockheed Martin established a Limit of Validity for 

L-1011-385 Series airplanes. The maintenance actions defined in Revision 3 of this Service 

Bulletin are necessary to ensure that the airplane will be free from widespread fatigue 

damage up to the Limit of Validity published in the L-1011 Maintenance Manual, Chapter 4 

Airworthiness Limitations Section, Paragraph 13. Revision 3 defines an inspection start 

point (ISP) at 13,875 flight cycles. Eddy Current Surface Scan (ECSS) inspections of the 

stringer end fittings of stringers 1 through 14 and 52 through 64 are to begin at this ISP time. 

A structural modification point (SMP) is defined at 20,800 flight cycles. Stringer end fittings 

of stringers 1 through 14 and 52 through 64 are to be replaced prior to this SMP time.

If cracks in the stringer end fittings go undetected, the cracks will propagate until the end 

fitting is severed. The load in the severed fitting redistributes to the adjacent fittings and, if 

those fittings have undetected cracks, the increased load will cause those cracks to propagate 

at a faster rate than the first fitting. This process continues until there are multiple damaged 

fittings adjacent to one another at which point the membrane and discontinuity loads in the 

aft pressure dome are redistributed to the fuselage skin by shear-bending of the vertical leg of 

the aft pressure bulkhead ring inner and outer tee caps (1503620). This bending induces a 

circumferential fatigue crack in the tee cap vertical leg. Once this crack reaches its critical 

length, the result is a rapid decompression similar to that experienced in the aforementioned 

incident.
April 1, 1992 093-53-105

Rev. 3, May 31, 2013 Page 3

This is a time compliance service bulletin containing both structural inspections and 

modifications. The service bulletin was originally issued as API 093-53-105 (Advanced 

Planning Information).

C. SAFETY INTENT

The safety intent of this service bulletin is to prevent simultaneous failure of multiple stringer 

end fittings at the aft pressure bulkhead which could lead to rapid decompression of the 

fuselage. Repetitive inspections and modification the stringer end fittings prior to the SMP 

will ensure structural integrity of the aft pressure bulkhead.

D. DESCRIPTION

Inspection Start Point (ISP): The initial inspection for widespread fatigue damage in the aft 

pressure bulkhead stringer end fittings is to be accomplished at or prior to the ISP of 13,875

flight cycles. These inspections are to be repeated at an interval of 1,750 flight cycles until 

the SMP is reached. The stringer-to-aft pressure bulkhead end fittings at stringer locations 1 

through 14 and 52 through 64 are Eddy Current Surface Scan (ECSS) inspected on aircraft 

with a small (29" wide) aft passenger door. For aircraft with a large (47" wide) aft passenger 

door, the stringer-to-aft pressure bulkhead end fittings at stringer locations 1 through 11, 14, 

52, and 55 through 64 are ECSS inspected. The remaining four end fittings at stringer 

locations 12, 13, 53, and 54 are inspected optically with an additional ECSS inspection of the 

skin at the four stringer locations. Any cracked fittings shall be replaced with new fittings. 

At locations where the stringer end fitting has to be replaced, ECSS, BHEC, and borescope 

inspect the aft pressure bulkhead ring inner and outer tee caps. Access for this inspection is 

accomplished by removing applicable ceiling panels and components in the aft 

lavatories/galley, access panels and negative pressure relief valves. On aircraft with a large 

aft passenger door, the door mechanism units must be removed.

Structural Modification Point (SMP): The required modification to protect against 

widespread fatigue damage in the aft pressure bulkhead stringer end fittings is to be 

accomplished at or prior to the SMP of 20,800 flight cycles. The modification includes 

replacement of the stringer end fittings of stringers 1 through 14 and 52 through 64 with new 

fittings. Completion of this modification eliminates the repeat inspections for a period of 

13,875 flight cycles after the modification. The repeat ECSS inspections are required again 

at approximately 34,000 flight cycles and are continued at an interval of 1,750 flight cycles 

until reaching the LOV of the airplane.

E. APPROVAL

The EFFECTIVITY information of Section 1, Paragraph A.(1) and the technical content of the 

ACCOMPLISHMENT INSTRUCTIONS of Section 2 of this service bulletin are FAA approved.

F. MANPOWER

Since the work described in this service bulletin has not been performed at a Lockheed Martin 

facility, the estimated man-power has not been validated and should not be used in making 

fixed price quotes for accomplishment of the work. The following estimates are provided only 

for planning purposes:
April 1, 1992 093-53-105

Rev. 3, May 31, 2013 Page 4

Activity Per Fitting

(man hours)

All Stringers

1-14 & 52-64

(man hours)

Gain Access 4.0 4.0

Inspection 0.5 13.5

End Fitting Replacement 6.0 162.0

Return Aircraft to Service 5.0 5.0

Inspection Only Total 9.5 22.5

Inspection & Replacement Total 15.5 184.5

G. MATERIAL

Parts and materials listed in Section 2, Tables 1, 2, and 3, in addition to replacement 

fasteners, paint, and other material are to be supplied/fabricated by the aircraft 

owner/operator.

H. TOOLING

The following equipment and accessories (or equivalent) are required for accomplishment of 

the inspections. Supplier contact is provided for current price and availability.

(1) Zetec MIZ-20A Eddy Current Tester, PN 2000-00-00

Procure from:

Zetec Inc.

1370 N.W. Mall St., P.O. Box 140,

Issaquah, WA 98027-0140 USA

Phone: (206) 392-5316 TLX 15 2592,

Fax (206) 392-2086

(2) Connector cable, PN VM99BM.

(2) Fingertip probe, ferrite shielded, 45 degree, PN VM745FTS with 5/8" length probe.

(3) Unshielded manual bolt hole probe, PN VM101B-XXX (XXX = probe diameter)

(5) Calibration Reference Standard, PN VM89A

Procure from:

VM Products Inc.

P.O. Box 44926, Tacoma, WA 98444-0926

Phone (206) 841-2939.

(6) Flexible borescope with a 0.100" D to 0.240" D, 48" long reach and single axis 

manipulation, with direct or fore-oblique objective lens (or equivalent).

NOTE: Equivalent borescope equipment may be a combination of rigid and/or flexible 

borescopes with direct, fore-oblique, and right angle viewing, as long as there is 

sufficient length to reach the area of interest and appropriate objective lens 

angles to ensure complete inspection.
April 1, 1992 093-53-105

Rev. 3, May 31, 2013 Page 5

Procure from:

Olympus America, Inc.

Industrial Products Group

Two Corporate Center Drive

Melville, NY 11747-3157

Telephone: (516) 844-5888

(800) 446-5260

I. WEIGHT AND BALANCE

Not affected.

J. ELECTRICAL LOAD DATA

Not affected.

K. REFERENCES

Airworthiness Directive (AD): AD95-18-52, Issued September 6, 1995 (Superseded)

AD95-26-11, Effective January 11, 1996

API 093-53-105

(Advanced Planning Information)

Service Bulletin: 093-11-126

093-53-270

Maintenance Manual: 4-00-00

6-40-00

20-51-02

25-31-00

25-42-00

25-43-10

29-11-00

52-12-00

Structural Repair Manual (SRM): 51-23-01

51-40-01

51-40-02

53-11-00, Figure 810

53-31-00, Figure 832, Sheet 6

Overhaul Manual (OHM): 20-72-01

20-76-03

20-77-13

20-78-06

20-78-07
April 1, 1992 093-53-105

Rev. 3, May 31, 2013 Page 6

L. OTHER PUBLICATIONS AFFECTED

None.

M. CORRESPONDENCE

Please reference this service bulletin number and direct all correspondence pertaining to this 

service bulletin, except purchase orders, to:

LOCKHEED MARTIN AERONAUTICS COMPANY

L1011 Technical Support Center

86 South Cobb Drive

Department 6A4M, Zone 0579

Marietta, GA 30063-0579, USA

Telephone: (770) 494-5444

FAX: (770) 494-5445

Email: L1011.support@lmco.com
April 1, 1992 093-53-105

Rev. 3, May 31, 2013 Page 7

2. ACCOMPLISHMENT INSTRUCTIONS

NOTE: This service bulletin is based on as-delivered condition of aircraft by Lockheed Martin to 

original purchaser. In addition, Lockheed Martin has taken into account other known 

Lockheed Martin service bulletins and/or modifications mandated by the FAA.

WARNING: FOR THE STRINGER END FITTING INSPECTION OR MODIFICATION, 

ENSURE ALL FOUR HYDRAULIC SYSTEMS ARE SHUT OFF IN ACCORDANCE 

WITH MAINTENANCE MANUAL 29-11-00. PLACARD FLIGHT 

ENGINEER/SECOND OFFICERS HYDRAULIC SYSTEM PANEL, ZONE 215, AND 

THE HYDRAULIC SERVICE PANEL, ZONE 147. INSTALL A FLIGHT CONTROL 

COLUMN LOCK IN FLIGHT STATION.

A. PREPARATION FOR STRINGER END FITTING INSPECTION OR MODIFICATION

(1) For aircraft with aft lavatories, gain access to the fittings by removing ceiling panels at the 

aft lavatories, reference Maintenance Manual 25-42-00. Pull back the insulation 

surrounding the stringer end fittings.

(2) For aircraft with aft lavatories, disconnect the electrical connector from the electric razor 

power supply on top of applicable ceiling panels, reference Maintenance Manual 25-43-10.

(3) For aircraft with aft galley, remove necessary galley components as required for access;

reference Maintenance Manual 25-31-00.

(4) Gain access to aft side of the pressure bulkhead through fire bottle inspection panel 

317BB; reference Maintenance Manual 6-40-00.

(5) For aircraft with a large (47" wide) aft passenger door, remove the door mechanism units;

reference Maintenance Manual 52-12-00.

(6) Remove dirt, grease, loose paint, and any other foreign matter from the area to be 

inspected e.g., rough surfaces, chipping, gummy residue.

B. AFT PRESSURE BULKHEAD REQUIRED INSPECTION

(1) Inspection Periods

(a) Inspection Start Point (ISP): At or before 13,875 flight cycles.

(b) Repeat Inspection: After the ISP, inspect every 1,750 flight cycles thereafter until 

reaching the SMP specified in Section 2.E.

(2) Temporary Deviations to the Inspection and Repair Requirements

(a) It is permissible to fly the aircraft with cracked (not severed) stringer end fittings 

prior to the SMP provided there are two (2) or more adjacent fittings on both sides of 

the cracked fitting that have been proven to be crack free by an Eddy Current Surface 

Scan (ECSS) inspection. Repeat the ECSS inspection of the adjacent fittings every 

600 flight cycles until the cracked fittings are replaced. The cracked fittings shall be 
April 1, 1992 093-53-105

Rev. 3, May 31, 2013 Page 8

replaced within 1,750 total flight cycles after finding the crack but not to exceed the 

SMP.

(b) The inspection, specified in Paragraphs 2.B.(3)(c), 2.B.(4)(a)3 and 2.B.(4)(b)4, of the 

inner and outer tee caps that are under the cracked fittings noted above may also be 

deferred until the cracked fittings are replaced, but not to exceed the SMP.

(3) For aircraft with a small (29" wide) aft passenger door (Serial No. 193A, B, C, E, L, M, P, 

R, S, T, and U)

(a) Stringer End Fittings

1 Inspect the end fittings at stringer locations 1 through 14 and 52 through 64 in the 

zones shown in Figure 1 using the Eddy Current Surface Scan procedure specified 

in Paragraph 2.C. Refer to Figure 3 for aircraft Serial No. -1002 through -1012 

and Figure 4 for aircraft Serial No. -1013 and up.

2 Any cracked end fitting shall be replaced with a new fitting without pilot holes. 

(See Tables 1, 2, and 3 for part numbers) If fitting is replaced, rework applicable 

new end fitting in accordance with Figure 6 or 7.

NOTE: Modify the FS 1792 frame in accordance with the SRM, Section 53-31-00,

Figure 832, Sheet 6 to facilitate the removal and installation of the fitting.

(b) 1503617 Upper Bonded Bulkhead Assembly Splice Tab

1 Eddy Current Surface Scan (ECSS) inspect the lower (or inner) surface of the 

1503617 upper bonded bulkhead assembly splice tab at stringer 1 through 14 and 

52 through 64 (27 places). Reference Figure 2 for the aft limit for this inspection. 

Use special care inspecting around the six (6) fasteners shown in View A of 

Figure 2. If there is a crack indication at a fastener, remove the fastener and 

perform a Bolt Hole Eddy Current (BHEC) inspection of the 1503620 inner tee cap 

forward flange per Paragraph 2.C.(2)(c).

2 If the inner tee cap is cracked, repair per SRM, Section 53-11-00, Figure 810.

3 If the upper bonded bulkhead assembly splice tab is cracked, contact Lockheed 

Martin Engineering for assistance. Provide detail crack data: location, 

orientation, length, etc.

(c) 1503620 Inner and Outer Tee Caps

1 If the ECSS inspection of Paragraph 2.B.(3)(a) reveals a stringer end fitting 

cracked (not completely severed), remove the damaged fitting and perform the 

following inspection:

a BHEC (Paragraph 2.C.(2)(c)) inspect the six (6) fastener holes in the 1503620 

inner tee cap forward flange, reference Figure 2, View A.

b If the inner tee cap is cracked, repair per the SRM, Section 53-11-00, 

Figure 810.
April 1, 1992 093-53-105

Rev. 3, May 31, 2013 Page 9

2 If the ECSS inspection of Paragraph 2.B.(3)(a) reveals a stringer end fitting 

severed, remove the damaged fitting and perform the following inspections:

a BHEC (Paragraph 2.C.(2)(c)) inspect the six (6) fastener holes in the 1503620 

inner tee cap forward flange, reference Figure 2, View A.

b ECSS inspect the 1503620 inner tee cap vertical leg on the forward side in the 

area of the 0.19 inch fillet radius. Inspect 3.6 inches on both sides of the 

stringer datum, reference Figure 2.

NOTE: A borescope inspection from the aft side is an optional method. Access 

may be gained through the negative pressure relief valve ports or by 

inserting the probe through the 0.250 inch diameter attach holes (see 

Figure 10) and articulating the flexible borescope in order to view the 

area. See the SRM, Section 51-23-01 and Paragraph 2.D. for the 

borescope inspection requirements.

c ECSS inspect the 1503620 outer tee cap vertical leg on the forward side just 

above the edge of the inner tee cap vertical leg. Inspect 3.6 inches on both 

sides of the stringer datum, reference Figure 2. If the inspector cannot get the 

Eddy current probe in close to the edge of the part, then perform a borescope 

inspection from the aft side (see the note above).

d If the inner or outer tee cap is cracked, repair per the SRM, Section 53-11-00, 

Figure 810.

NOTE: The inspection requirements of Paragraph 2.B.(3)(c) are applicable to 

damaged stringer end fittings that are replaced after receipt of 

Revision 1 of this service bulletin.

(4) For aircraft with a large (47" wide) aft passenger door (Serial No. 193G, H, J, K, N, V, W, 

Y, 293A, B, C, and F)

(a) Stringer locations 1 through 11, 14, 52, and 55 through 64

1 Stringer End Fittings

a Inspect the end fittings at stringer locations 1 through 11, 14, 52, and 55 

through 64 in the zones shown in Figure 1 using the Eddy Current Surface 

Scan procedure specified in Paragraph 2.C. Refer to Figure 3 for aircraft 

Serial No. -1002 through -1012 and Figure 4 for aircraft Serial No. -1013 and 

up.

b Any cracked end fitting shall be replaced with a new fitting without pilot holes. 

(See Tables 1, 2, and 3 for part numbers) If fitting is replaced, rework 

applicable new end fitting in accordance with Figure 6 or 7.

NOTE: Modify the FS 1792 frame in accordance with the SRM, Section 

53-31-00, Figure 832, Sheet 6 to facilitate the removal and installation 

of the fitting.

2 1503617 Upper Bonded Bulkhead Assembly Splice Tab
April 1, 1992 093-53-105

Rev. 3, May 31, 2013 Page 10

a Eddy Current Surface Scan (ECSS) inspect the lower (or inner) surface of the 

1503617 upper bonded bulkhead assembly splice tab at stringer 1 through 11, 

14, 52, and 55 through 64. Reference Figure 2 for the aft limit for this 

inspection. Use special care inspecting around the six (6) fasteners shown in 

View A of Figure 2. If there is a crack indication at a fastener, remove the 

fastener and perform a Bolt Hole Eddy Current (Paragraph 2.C.(2)(c))

inspection of the 1503620 inner tee cap forward flange.

b If the inner tee cap is cracked, repair per the SRM, Section 53-11-00, 

Figure 810.

c If the upper bonded bulkhead assembly splice tab is cracked, contact Lockheed 

Martin Engineering for assistance. Provide detail crack data: location, 

orientation, length, etc.

3 1503620 Inner and Outer Tee Caps

a If the ECSS inspection of Paragraph 2.B.(4)(a)1 reveals a stringer end fitting 

cracked (not completely severed), remove the damaged fitting and perform the 

following inspection:

(1) BHEC (Paragraph 2.C.(2)(c)) inspect the six (6) fastener holes in the 

1503620 inner tee cap forward flange, reference Figure 2, View A.

(2) If the inner tee cap is cracked, repair per the SRM, Section 53-11-00, 

Figure 810.

b If the ECSS inspection of Paragraph 2.B.(4)(a)1 reveals a stringer end fitting 

severed, remove the damaged fitting and perform the following inspections:

(1) BHEC (Paragraph 2.C.(2)(c)) inspect the six (6) fastener holes in the 

1503620 inner tee cap forward flange, reference Figure 2, View A.

(2) ECSS inspect the 1503620 inner tee cap vertical leg on the forward side in 

the area of the 0.19 inch fillet radius. Inspect 3.6 inches on both sides of 

the stringer datum, reference Figure 2.

NOTE: A borescope inspection from the aft side is an optional method. 

Access may be gained through the negative pressure relief valve 

ports or by inserting the probe through the 0.250 inch diameter 

attach holes (see Figure 10) and articulating the flexible 

borescope in order to view the area. See the SRM, Section 

51-23-01 and Paragraph 2.D. for the borescope inspection 

requirements.

(3) ECSS inspect the 1503620 outer tee cap vertical leg on the forward side 

just above the edge of the inner tee cap vertical leg. Inspect 3.6 inches on 

both sides of the stringer datum, reference Figure 2. If the inspector 

cannot get the Eddy current probe in close to the edge of the part, then 

perform a borescope inspection from the aft side (see the note above).
April 1, 1992 093-53-105

Rev. 3, May 31, 2013 Page 11

(4) If the inner or outer tee cap is cracked, repair per the SRM, Section 

53-11-00, Figure 810.

NOTE: The inspection requirements of Paragraph 2.B.(4)(a)3 are 

applicable to damaged stringer end fittings that are replaced after

receipt of Revision 1 of this service bulletin.

(b) Stringer locations 12, 13, 53, and 54

1 Stringer End Fittings

a Optically inspect, using a borescope, the end fitting at stringer locations 12, 13, 

53, and 54 in the zones shown in Figure 1. Refer to Figure 3 for aircraft Serial 

No. 1002 through 1012 and Figure 4 for aircraft Serial No. 1013 and up.

NOTE: See the SRM, Section 51-23-01 and Paragraph 2.D. for the borescope 

inspection requirements.

b Any cracked end fitting shall be replaced with a new fitting without pilot holes. 

(See Tables 1, 2, and 3 for part numbers.) If fitting is replaced, rework 

applicable new end fitting in accordance with Figure 6 or 7.

NOTE: Modify the FS 1792 frame in accordance with the SRM, Section 

53-31-00, Figure 832, Sheet 6 to facilitate the removal and installation 

of the fitting.

2 Aft Fuselage Skin (1542237, 1542238, 1611647)

a ECSS inspect the aft fuselage skin panel, L & RHS, around the sixteen (16) 

fasteners in fastener line number 1 and two (2) fasteners in fastener line 

number 2 (see Figure 5, Sheet 1).

b If the aft fuselage skin is cracked, contact Lockheed Martin Engineering for 

assistance. Provide detail crack data: location, orientation, length, etc.

3 1503617 Upper Bonded Bulkhead Assembly Splice Tab

a Eddy Current Surface Scan (ECSS) inspect the lower (or inner) surface of the 

1503617 upper bonded bulkhead assembly splice tab at stringer location 12, 13, 

53, and 54. Reference Figure 2 for the aft limit for this inspection. Use 

special care inspecting around the six (6) fasteners shown in View A of Figure 2. 

If there is a crack indication at a fastener, remove the fastener and perform a 

Bolt Hole Eddy Current (Paragraph 2.C.(2)(c)) inspection of the 1503620 inner 

tee cap forward flange.

b If the inner tee cap is cracked, repair per the SRM, Section 53-11-00, Figure 

810.

c If the upper bonded bulkhead assembly splice tab is cracked, contact Lockheed 

Martin Engineering for assistance. Provide detail crack data: location, 

orientation, length, etc.
April 1, 1992 093-53-105

Rev. 3, May 31, 2013 Page 12

4 1503620 Inner and Outer Tee Caps

a If the optical inspection of Paragraph 2.B.(4)(b)1 reveals a stringer end fitting 

cracked (not completely severed), remove the damaged fitting and perform the 

following inspection:

(1) BHEC (Paragraph 2.C.(2)(c)) inspect the six (6) fastener holes in the 

1503620 inner tee cap forward flange, reference Figure 2, View A.

(2) If the inner tee cap is cracked, repair per the SRM, Section 53-11-00, 

Figure 810.

b If the optical inspection of Paragraph 2.B.(4)(b)1 reveals a stringer end fitting 

severed, remove the damaged fitting and perform the following inspections:

(1) BHEC inspect the six (6) fastener holes in the 1503620 inner tee cap 

forward flange, reference Figure 2, View A.

(2) ECSS inspect the 1503620 inner tee cap vertical leg on the forward side in 

the area of the 0.19 inch fillet radius. Inspect 3.6 inches on both sides of 

the stringer datum, reference Figure 2.

NOTE: A borescope inspection from the aft side is an optional method. 

Access may be gained through the negative pressure relief valve 

ports or by inserting the probe through the 0.250 inch diameter 

attach holes (see Figure 10) and articulating the flexible 

borescope in order to view the area. See the SRM, Section 

51-23-01 and Paragraph 2.D. for the borescope inspection 

requirements.

(3) ECSS inspect the 1503620 outer tee cap vertical leg on the forward side 

just above the edge of the inner tee cap vertical leg. Inspect 3.6 inches on 

both sides of the stringer datum, reference Figure 2. If the inspector 

cannot get the Eddy current probe in close to the edge of the part, then 

perform a borescope inspection from the aft side (see the note above).

(4) If the inner or outer tee cap is cracked, repair per the SRM, Section 

53-11-00, Figure 810.

NOTE: The inspection requirements of Paragraph 2.B.(4)(b)4 are 

applicable to damaged stringer end fittings that are replaced after

receipt of Revision 1 of this service bulletin.

(5) Report all crack findings to Lockheed Martin L1011 Technical Support Center.
April 1, 1992 093-53-105

Rev. 3, May 31, 2013 Page 13

C. EDDY CURRENT SURFACE SCAN (ECSS)

(1) Equipment Set-up

NOTE: Do not connect the probe and connector, prior to turning the instrument on,

otherwise a normal failure message will occur during the "self test".

(a) Hold the ON/OFF switch in for approximately 1 second and release. The power 

turns on when the switch is released. The instrument will go through a brief

self-test cycle, after which the setup menu will be displayed on the screen. To 

turn-on/off the back-light, briefly depress the ON/OFF switch.

(b) If internal power is utilized, ensure that the battery condition is acceptable; the 

battery voltage readout can be accessed at any time by placing the instrument in 

HOLD mode. The voltage also appears automatically whenever it is below 9.6 volts, 

where about 30 minutes of useful battery life remains.

(c) Attach the cable to the probe and "SINGLE" probe connector on the instrument.

(d) INITIAL ADJUSTMENTS - Establish the settings provided by Figure 8, "A. INITIAL 

SETUP".

(e) FINAL ADJUSTMENTS PRIOR TO INSPECTION: Details for balancing the 

instrument, responses to various indications from the reference standard (typical 

cracks), similar to those that will be observed from the stringer fittings, and scanning 

with finger probe, are provided by Figure 8 B through E. Use clear "CLR", balance 

"BAL", and "HOLD" functions, as required during the setup and inspection 

accomplishment.

(2) Eddy Current Surface Scan (ECSS) Inspection

(a) ECSS: Except as noted in Paragraph 2.B.(4)(b)1a, scan the areas around the 

stringer end fitting flange transitions, fasteners and end pad fillet radii (reference 

Figure 1); and around the fasteners (line No. 1 and No. 2) in the aft fuselage skin at 

stringers 12, 13, 53, and 54 on aircraft with a large aft passenger door (reference 

Figure 5). Also scan the lower surface of the upper bonded bulkhead assembly splice 

tabs, reference Figure 2. Wherever a severed stringer end fitting is removed for 

repair purposes, scan the aft pressure bulkhead ring inner and outer tee cap vertical 

leg, reference Figure 2. Use of the audible alarm will reduce the difficulties of 

visually monitoring the scope, while concentrating on scanning around the fasteners 

and other suspect areas. This is especially helpful while performing the inspection 

overhead from a ladder. Upon alarm activation, verify responses on the scope prior 

to marking suspect crack areas. For those areas such as the radii, where the Finger 

Probe may become difficult to manipulate from the index finger, it may be 

advantageous to use two fingers for easier reach.

(b) VERIFICATION OF SUSPECT CRACKS: Use visual aids such as a flexible 

borescope or magnification for verification. Where verification requires further 

evaluation, Bolt Hole Eddy Current (BHEC) may be required, as follows in Step (c).
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Rev. 3, May 31, 2013 Page 14

(c) BHEC: Wherever the stringer end fitting is removed for repair or modification

purposes, BHEC inspect the six (6) fastener holes in the aft pressure bulkhead ring 

inner tee cap forward flange, reference Figure 2, View A. In addition, upon 

identification of the suspect cracks found by the ECSS inspection (Paragraph 

2.C.(2)(a)), BHEC inspection may be required to confirm crack indications. Fastener 

removal must first be accomplished per the established acceptable maintenance 

practices. Accomplish the setup requirements for bolt-hole probes using the most 

representative corresponding diameter hole in the reference standard or the EDM 

notches. Scan holes anticipating a response when the sensor passes the EDM notch 

or point of suspected crack propagation. Use the setup established for the BHEC 

inspection, as provided by Figure 9. Ensure that false indications are not perceived 

from layer interfaces, burrs, or gouges.

D. BORESCOPE INSPECTION

(1) Equipment set-up

(a) Assemble the borescope per the manufacturer's instructions.

(b) Check optics; ensure that the optics are clean and undamaged.

(c) Check illumination; check the light source to ensure that it is adequate for the task; 

batteries and bulbs are good, cooling fans are operable, optical connectors and cables 

are in good condition, as applicable.

(2) Pre-inspection preparation; familiarization and tooling requirements

NOTE: It is important that the inspector be familiar with the sometimes abstract visual 

images encountered using borescopes. These may result from a combination of 

optical diffraction and internal surface conditions or finishes. Even with 

minimal magnification, images may be magnified substantially due to the effects 

of exceptional near-field resolution obtainable with some borescopes. Confusing 

"tunnel-vision" effects may result in overlooking very large defects if the 

configuration under evaluation is not well understood.

(a) Gain familiarity with structure and optical images; examine samples of parts with a 

variety of expected conditions, both acceptable and otherwise.

(b) Avoid damage; gain familiarity with inherent structural design obstacles which may 

require avoidance, to protect the borescope optics and/or lighting features from 

damage.

(c) Inspect per the requirements of Paragraphs 2.B.(3)(c)2b and c, 2.B.(4)(a)3b(2) and (3), 

2.B.(4)(b)1a, and 2.B.(4)(b)4b(2) and (3).
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E. AFT PRESSURE BULKHEAD REQUIRED MODIFICATION

The Structural Modification Point (SMP) for the aft pressure bulkhead is 20,800 flight cycles. 

The structural modification involves removing and replacing all stringer end fittings at 

stringers 1 through 14 and 52 through 64. This required modification must be implemented 

at or prior to the SMP.

NOTE: If an end fitting was replaced prior to 20,800 flight cycles in accordance with 

2.B.(3)(a)2 or 2.B.(4)(a)1b or 2.B.(4)(b)1b, then it does not need to be replaced as part 

of this required modification. However, the repeat visual and ECSS inspections 

specified in Paragraph 2.B. shall begin on that end fitting not later than 13,875 flight 

cycles after the time of replacement. If the time of replacement is not documented, 

then the end fitting shall be replaced during this required modification.

(1) Perform the inspections of paragraphs 2.B.(3)(b) & (c), 2.B.(4)(a)2 & 3, and/or 

2.B.(4)(b)2, 3 & 4, as applicable, at the time of this required modification.

(2) Remove every third stringer end fitting between stringers 1 through 14 and 52 through 64. 

There shall be two (2) or more adjacent fittings installed on both sides of the removed 

fitting except at stringers 13, 14, 52, 53 which are adjacent to the WL 280 Upper Longeron.

(3) Replace the removed fittings with new end fittings without pilot holes. See Tables 1, 2 

and 3 for part numbers. Rework applicable new end fittings in accordance with Figure 6 

or 7.

(4) In the event that new end fittings cannot be fabricated per blueprint or procured from 

spares stock, the removed fittings may be refurbished as follows:

(a) Identify each removed end fitting with respect to its stringer location. Each end 

fitting must be reinstalled in its original location.

(b) Remove paint from each end fitting per OHM 20-76-03.

(c) Perform penetrant inspection per OHM 20-72-01. Scrap any end fitting that meets 

the criteria for rejection and replace with a new end fitting without pilot holes. See 

Tables 1, 2 and 3 for part numbers. Rework applicable new end fittings in accordance 

with Figure 6 or 7.

(d) Perform BHEC inspection of all fastener holes in each fitting per Paragraph 2.C.(2)(c).

(e) Any end fitting that meets the acceptance criteria of both penetrant and BHEC

inspections may be refinished per OHM 20-78-06 & 20-78-07, identified per OHM 

20-82-01, and reinstalled in the aircraft at the original stringer location per Notes 1 

and 2 of Figure 3 or Note 1 of Figure 4.

(5) Repeat steps (1) through (4) until all stringer end fittings have been replaced.
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F. AFT PRESSURE BULKHEAD POST-MODIFICATION INSPECTION

Start the inspections of Paragraph 2.B. at 13,875 flight cycles after accomplishing the 

modification of Paragraph 2.E.

G. RESTORATION FOLLOWING STRINGER END FITTING INSPECTION OR 

MODIFICATION

(1) Reinstall access panel, ceilings panels and components removed during the inspection, 

reference Maintenance Manuals 6-40-00, 25-31-00, and 25-42-00.

(2) If required, reconnect the electrical connector to the electric razor power supplies removed 

during the inspection in accordance with Maintenance Manual 25-43-10.

(3) Remove all tags and placards installed during the inspection.

(4) Restore hydraulic power shut off during the inspection in accordance with Maintenance 

Manual 29-11-00.

(5) Restore door mechanism units on aircraft with a large (47" wide) aft passenger door;

reference Maintenance Manual 52-12-00.
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Table 1

For Aircraft Serial -1002 Through -1012

STRINGER No.

LH SIDE

STRINGER No.

RH SIDE

ORIGINAL

FITTING

 TO BE INSPECTED [1]

BLANK

REPLACEMENT

FITTING

- 1 1507258-102 * 1554944-102

64 2 1507292-101/-102 * 1554944-101/-102

63 3 1507293-101/-102 * 1554945-101/-102

62 4 1507294-101/-102 * 1554946-101/-102

61 5 1507295-101/-102 * 1554947-101/-102

60 6 1507296-101/-102 * 1554948-101/-102

59 7 1507297-101/-102 * 1554949-101/-102

58 8 1507298-101/-102 * 1554950-101/-102

57 9 1507299-101/-102 * 1554951-101/-102

56 10 1507300-101/-102 * 1554952-101/-102

 55 [2] 11 [2] 1507301-101/-102 * 1554953-101/-102

 54 [2] 12 [2] 1507302-101/-102 * 1554954-101/-102

 53 [2] 13 [2] 1507303-101/-102 * 1554955-101/-102

 52 [2] 14 [2] 1507304-101/-102 ** 1507304-101/-102

* Make from 1554943-101/-102 Forging. Reference Figure 6 for rework.

** Make from 1507257-101/-102 Forging. Reference Figure 7 for rework.

[1] Stringer end fitting located on the forward side of the aft pressure bulkhead ring (1503620).

[2] The noted fitting locations were excluded in AD 95-18-52 but included in AD95-26-11. The area 

of inspection was expanded as part of an overall plan to ensure inspection of all aft pressure 

bulkhead tension fittings.
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Table 2

For L-1011-1 Aircraft Serial -1013 and Up

STRINGER No.

LH SIDE

STRINGER No.

RH SIDE

ORIGINAL

FITTING

 TO BE INSPECTED [1]

BLANK

REPLACEMENT

FITTING

- 1 1554944-102 * 1554944-102

64 2 1554944-101/-102 * 1554944-101/-102

63 3 1554945-101/-102 * 1554945-101/-102

62 4 1554946-101/-102 * 1554946-101/-102

61 5 1554947-101/-102 * 1554947-101/-102

60 6 1554948-101/-102 * 1554948-101/-102

59 7 1554949-101/-102 * 1554949-101/-102

58 8 1554950-101/-102 * 1554950-101/-102

57 9 1554951-101/-102 * 1554951-101/-102

56 10 1554952-101/-102 * 1554952-101/-102

 55 [2] 11 [2] 1554953-101/-102 * 1554953-101/-102

 54 [2] 12 [2] 1554954-101/-102 * 1554954-101/-102

 53 [2] 13 [2] 1554955-101/-102 * 1554955-101/-102

 52 [2] 14 [2] 1507304-101/-102 ** 1507304-101/-102

* Make from 1554943-101/-102 Forging. Reference Figure 6 for rework.

** Make from 1507257-101/-102 Forging. Reference Figure 7 for rework.

[1] Stringer end fitting located on the forward side of the aft pressure bulkhead ring (1503620).

[2] The noted fitting locations were excluded in AD 95-18-52 but included in AD95-26-11. The area 

of inspection was expanded as part of an overall plan to ensure inspection of all aft pressure 

bulkhead tension fittings.
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Table 3

For L-1011-3 (-500) Aircraft Serial -1083 and Up

STRINGER No.

LH SIDE

STRINGER No.

RH SIDE

ORIGINAL

FITTING

 TO BE INSPECTED [1]

BLANK

REPLACEMENT

FITTING

- 1 1554944-102 * 1554944-102

64 2 1554944-101/-102 * 1554944-101/-102

63 3 1554945-101/-102 * 1554945-101/-102

62 4 1554946-101/-102 * 1554946-101/-102

61 5 1554947-101/-102 * 1554947-101/-102

60 6 1554948-101/-102 * 1554948-101/-102

59 7 1554949-101/-102 * 1554949-101/-102

58 8 1554950-101/-102 * 1554950-101/-102

57 9 1554951-101/-102 * 1554951-101/-102

56 10 1554952-101/-102 * 1554952-101/-102

55 [2] 11 [2] 1534199-101/-102 * 1534199-101/-102

54 [2] 12 [2] 1534198-101/-102 * 1534198-101/-102

53 [2] 13 [2] 1534197-101/-102 * 1534197-101/-102

52 [2] 14 [2] 1560820-101/-102 ** 1560820-101/-102

* Make from 1554943-101/-102 Forging. Reference Figure 6 for rework.

** Make from 1507257-101/-102 Forging. Reference Figure 7 for rework.

[1] Stringer end fitting located on the forward side of the aft pressure bulkhead ring (1503620).

[2] The noted fitting locations were excluded in AD 95-18-52 but included in AD95-26-11. The area 

of inspection was expanded as part of an overall plan to ensure inspection of all aft pressure 

bulkhead tension fittings.
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Inspection of Stringer End Fitting

Figure 1
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Aft Pressure BHD: Inner & Outer Tee Cap and

Upper Bonded BHD Assy Splice Tab Inspection

Figure 2
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Stringer End Fitting Inspection (SN -1002 through -1012)

Figure 3
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Stringer End Fitting Inspection (SN -1013 and Up)

Figure 4
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Skin Inspection

Figure 5 (Sheet 1)
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Skin Inspection

Figure 5 (Sheet 2)
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1554943-101/-102 Forging (Fitting) Rework

Figure 6
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1507257-101/-102 Forging (Fitting) Rework

Figure 7
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Eddy Current Surface Scan

Figure 8
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Bolt Hole Eddy Current

Figure 9
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Borescope Inspection Through Stringer

End Fitting Attachment Holes (Fitting Removed)

Figure 10
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3. MATERIAL INFORMATION

Parts and materials to accomplish these inspections are to be provided by the operator. (See 

Section 2, Paragraph E.)