P.O. Box 790490 • San Antonio, Texas 78279–0490 • (210) 824–9421

TO: HOLDERS OF SA26 SERIES SERVICE INFORMATION MANUALS

Attached is Revision 1 to SA26 Series Service Bulletin 26-53-001, Inspection of

F.S. 51.31 Forward Pressure Bulkhead for Cracks, Issued: September 26, 2013,

Revised: November 6, 2013.

Two aircraft have been inspected and found to have significant cracking of the

forward pressure bulkhead between stringers 8 and 10 on both LH and RH sides.

The cracks appear to be adjacent to the horizontal hat stiffeners in the radius of the

bulkhead frame. With the risk of cabin decompression due to cracks in the

bulkhead, this bulletin has been issued to request an immediate inspection of this

area.

Revision 1 corrects step 1.D. Change denoted by revision bar in left margin.

Please insert the attached revised Chapter 53 Index pages.
P.O. Box 790490 • San Antonio, Texas 78279–0490 • (210) 824–9421
CHAPTER 53 – FUSELAGE

Issued: September 26, 2013

Revised: November 6, 2013

CHAPTER 53 INDEX

Page 1 of 1

NUMBER DATE TITLE AIRCRAFT EFFECTIVITY

SA26 SERIES INDEX

26-53-001 09-26-13 Inspection of F.S. 51.31 All SA26-T/AT Series

(R) 11-06-13 Forward Pressure Bulkhead Airplanes

for Cracks
P.O. Box 790490 • San Antonio, Texas 78279–0490 • (210) 824–9421
Issued: September 26, 2013

Revised: November 6, 2013

26-53-001 R1

Page 1 of 8

SERVICE BULLETIN

SA26 SERIES

FUSELAGE

Inspection of F.S. 51.31 Forward Pressure Bulkhead for Cracks

1. PLANNING INFORMATION

A. Effectivity:

All SA26-T/-AT Airplanes

B. Reason:

Two aircraft have been inspected and found to have significant cracking of the

forward pressure bulkhead between stringers 8 and 10 on both LH and RH sides.

The cracks appear to be adjacent to the horizontal hat stiffeners in the radius of the

bulkhead frame. With the risk of cabin decompression due to cracks in the bulkhead,

this bulletin has been issued to request an immediate inspection of this area.

Revision 1 corrects step 1.D. Change denoted by revision bar in left margin.

C. Description:

Perform an initial detail visual inspection of the frame flange at F.S 51.31, looking

for cracking in the radius per step 2 instructions. If cracking is found, the operator

is required to contact M7 Aerospace for repair. A repetitive inspection is also

implemented with this bulletin.

D. Compliance:

Mandatory

For aircraft with more than 30,000 flight hours, perform the inspection within the next

150 flight hours from the date of this service bulletin.

For aircraft with 25,000 to 29,999 flight hours, perform the inspection within the next

300 flight hours from the date of this service bulletin.

For aircraft with 20,000 to 24,999 flight hours, perform the inspection within the next

450 flight hours from the date of this service bulletin.

For aircraft with 11,000 to 19,999 flight hours, perform the inspection within the next

600 flight hours from the date of this service bulletin.

For aircraft with less than 11,000 flight hours, perform the inspection at 11,000 flight

hours or within the next 600 flight hours from the date of this service bulletin,

whichever occurs later.

Repeat inspection interval for all aircraft is every 1,000 flight hours following the

initial/threshold inspection.
Issued: September 26, 2013

Revised: November 6, 2013

26-53-001 R1

Page 2 of 8

SERVICE BULLETIN

SA26 SERIES

Inspection requirements: See step 2.

If an owner/operator has evidence to demonstrate that an inspection of FAA

approved equivalent type has been performed within the three previous calendar

months from the date of this bulletin, this shall qualify for the initial/threshold

inspection. If this approved inspection qualifies, then the repeat inspection is every

1,000 hours from the time of that initial/threshold inspection.

E. Approval:

FAA Approved for Engineering Design.

F. Manpower:

M7 Aerospace estimates 12 man-hours (for both LH and RH sides) to accomplish

this service bulletin. This includes gaining access via the forward baggage compartment, removing sealant, perform detail visual inspection, and reinstallation This

estimate is for direct labor only, accomplished by an experienced crew. Adjust the

estimate with operator task hour data if necessary.

G. Material – Cost and Availability:

None

H. Tooling – Price and Availability:

No special tooling required.

I. Weight and Balance:

(a) For inspections only - None

(b) For installation of repair, if required. A weight of all repair parts shall be obtained

before installation. These parts are roughly located at F.S. 51.31. The AFM

weight and balance data shall be updated.

J. References:

M7 M-5609 Memorandum.

M7 Engineering Drawing 26-21015 (latest FAA approved revision), F.S. 51.31

bulkhead installation.

SA26 Letter Check "D".

NOTE: References are for manufacturer’s use only.

K. Other Publications Affected:

None
Issued: September 26, 2013

Revised: November 6, 2013

26-53-001 R1

Page 3 of 8

SERVICE BULLETIN

SA26 SERIES

2. ACCOMPLISHMENT INSTRUCTIONS

Inspect using an illumination device (such as circular fluorescent inspection luminaire)

which produces a minimum of 150 fc of light intensity at the part surface and a magnification

device (such as a watchmaker's loupe) producing approximately 8X magnification or

greater. Examine those surface details specified in the inspection requirements noting

defects as directed by the inspection requirements.

Inspection requirements for F.S. 51.31: Frame flange between stringers 8 and 10 on both

LH and RH side of the fuselage.

A. Disconnect power to the aircraft and tag out Battery and External Power

switches with placards to prevent injury to personnel or damage to the aircraft.

B. Gain access to the inspection area by removing equipment/liners/insulation in

the forward baggage compartment as required.

NOTE: Depending on aircraft model, this area can have several avionics boxes

mounted as well as the standard baggage bay liners and insulation.

C. Prepare the specific area for inspection by removing sealant and cleaning.

D. Perform a detail visual inspection (DVI) of the F.S. 51.31 frame flange, looking

for cracking in the radius of the frame flange. See Figures 1 through 4 for

location of inspection and typical cracks.

E. If cracking is found in radius, continue DVI of surrounding structure including

bulkhead web, and horizontal and vertical web stiffeners, looking for other signs

of damage such as cracking, loose or pulled fasteners.

F. Report all damage to M7 Aerospace at MetroTech@M7Aerospace.com or fax to

210-820-8626.

(1) Report specific crack locations, length, and orientation. Send photos or

sketches of all damage. Also please provide Aircraft serial number, total aircraft

hours, and total aircraft cycles.

G. Perform repair in accordance with M7 Aerospace serial number specific FAA

approved Limited Aircraft Repair (LAR) instructions.

H. If no cracking is found, it is permissible to reseal pressure boundary.

I. Reassemble/reinstall all equipment/liners/insulation removed in step B. per

applicable sections of the SA26 Maintenance Manual.

J. Remove all placards from Battery and External Power switches and reconnect

power to aircraft.
Issued: September 26, 2013

Revised: November 6, 2013

26-53-001 R1

Page 4 of 8

SERVICE BULLETIN

SA26 SERIES

K. Perform functional/operational checks on all systems that were disturbed per

SA26 Maintenance Manual.

L. Complete aircraft records in accordance with 14 CFR 43.9.

M. Complete and return service bulletin compliance form to M7 Aerospace
Issued: September 26, 2013

Revised: November 6, 2013

26-53-001 R1

Page 5 of 8

SERVICE BULLETIN

SA26 SERIES

FIGURE 1

FS 51.31 FWD PRESSURE BULKHEAD (26-21015)

Stringer 8L

Stringer 9L

Stringer 10L

Typical cracking

along frame radius

between stringers 8

to 9, and 9 to 10.

LEFT HAND SIDE 

SHOWN

RIGHT HAND SIDE

OPPOSITE

VIEW LOOKING AFT
Issued: September 26, 2013

Revised: November 6, 2013

26-53-001 R1

Page 6 of 8

SERVICE BULLETIN

SA26 SERIES

FIGURE 2

RHS VIEW OF BULKHEAD WITH CRACKS NOTED (TYPICAL)

(VIEW LOOKING AFT INSIDE FWD BAGGAGE COMPARTMENT)

Stringer 8

Stringer 9
Issued: September 26, 2013

Revised: November 6, 2013

26-53-001 R1

Page 7 of 8

SERVICE BULLETIN

SA26 SERIES

FIGURE 3

LHS VIEW OF BULKHEAD WITH CRACKS NOTED (TYPICAL)

(VIEW LOOKING AFT INSIDE FWD BAGGAGE COMPARTMENT)

Stringer 9
Issued: September 26, 2013

Revised: November 6, 2013

26-53-001 R1

Page 8 of 8

SERVICE BULLETIN

SA26 SERIES

FIGURE 4

TYPICAL CRACK LOCATION

(VIEW WITH EXTERNAL FUSLAGE SKIN REMOVED)

CRACK
SERVICE BULLETIN COMPLIANCE FORM

26-53-001 R1

TO: OPERATOR OR SERVICE FACILITY ACCOMPLISHING BULLETIN

Please complete this compliance form, and mail according to the instructions on the

reverse side.

Thank you for returning this form.

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *

Aircraft Model Aircraft Serial Number

Bulletin Issue Date Revision Date

Aircraft Registration Number

Operator/Owner

Time on Aircraft

Date Accomplished

Comments
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