P.O. Box 790490 • San Antonio, Texas 78279–0490 • (210) 824–9421 TO: HOLDERS OF SA226 SERIES SERVICE INFORMATION MANUALS
Attached is Revision 1to SA226 Series Service Bulletin226-53-017, Inspection of F.S. 69.31 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) 824–9421Issued: February 08, 1971 Revised: February 17, 1992 CHAPTER 53 INDEX Page 1 of 2 NUMBER DATE TITLE AIRCRAFT EFFECTIVITY SA226 SERIES INDEX CHAPTER 53 – FUSELAGE

53-001 02-08-71 Frame Splices - SA226-T, S/N T201-210. (R)01-22-76 Inspect and Change As Required 53-002 02-23-71 Installation of SA226-T, S/N T201-209, (R)01-22-76 Doubler SA226-AT, S/N AT001-002, SA226-TC, S/N TC201-202. 53-003 09-16-77 Reinforced Floorboard SA226-T, S/N T201-278, In Nose Baggage SA226-AT, S/N AT001-060, Compartment SA226-TC, S/N TC201-238.
53-004 09-27-77 Drain Holes SA226-T, S/N T246-276, SA226-AT, S/N AT001-054, SA226-TC, S/N TC201-227.
53-005 11-15-78 Aft Wing to Fuselage SA226-T, S/N T201-278, Belly Fairing SA226-AT, S/N AT001-059, Reinforcement SA226-TC, S/N TC201-232.
53-006 11-24-80 Inspection/Repair SA226-T, S/N T201-275, of Fuselage Belly T277 and T291, Skin SA226-AT, S/N AT001-074, SA226-TC, S/N TC201-407. 53-007 05-07-81 Inspection/Beef-Up SA226-AT, S/N AT001-074, (R)03-27-87 ofCargo Door Area SA226-TC, S/N TC201-419. (R)02-17-92 Belt Frames Category III
53-008 11-12-81 Stiffening of Cargo SA226-AT, S/N AT001-419, Door Opening and SA226-TC, S/N TC201-419. Cargo Floor
53-009 03-30-82 Fuselage - Radome SA226-T, S/N T275 and Drain T277-291, SA226-T(B), S/N T(B)276 and T(B)292-417, SA226-AT, S/N AT063-074, SA226-TC, S/N TC232-419.CHAPTER 53 INDEX Page 2 of 2 NUMBER DATE TITLE AIRCRAFT EFFECTIVITY SA226 SERIES INDEX CHAPTER 53 – FUSELAGE

Issued: February 08, 1971 Revised: November 6, 2013 53-010 02-23-84 Inspection and/or SA226-T, S/N T201-275, (R)03-29-84 Repair FuselageSkin T277-291, Cracks SA226-T(B), S/N T(B)276, T(B)292-417, SA226-AT, S/N AT001-074, SA226-TC, S/N TC201-419.
53-011 01-18-93 Cabin Entrance Door SA226-AT, S/N AT001-074, (R)02-10-93 Sill Beef Up SA226-TC, S/N TC201, 406, and 419. 53-012 09-22-94 Cockpit Floorboard FOD AllSA226 Series Airplanes (R)06-05-96 Barrier Installation 53-013 11-07-07 Radome Lightning All SA226 Series Airplanes Protection 53-014 09-03-10 Installation of Form-in-Place All SA226 Series Airplanes Gaskets - Wing-to-Body Fairings 53-015 10-08-10 AccessPanels Installation All SA226 Series Airplanes (R) 01-26-11 53-016 07-27-12 Inspection and/or Replacement All SA226 Series Airplanes (R) 05-13-13 of the Left Hand and Right Hand Forward Wing-to-Body Attach Fittings 53-017 09-26-13 Inspection of F.S. 69.31 All SA226 Series Airplanes (R) 11-06-13 Forward Pressure Bulkhead for CracksIssued: September 26, 2013 Revised: November 6, 2013 226-53-017 R1 Page 1 of 8 

# SERVICE BULLETIN SA226 SERIES



### FUSELAGE Inspection of F.S. 69.31 Forward Pressure Bulkhead for Cracks 1. PLANNING INFORMATION A. Effectivity: All SA226 Series 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 69.31, 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 226-53-017 R1 Page 2 of 8 

# SERVICE BULLETIN SA226 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 accomplishthis 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. 69.31. The AFM weight and balance data shall be updated. J. References: M7 M-5609 Memorandum. M7 Engineering Drawing 27-21000 (latest FAA approved revision), F.S. 69.31 bulkhead installation. M7 Engineering Drawing 27-21028 (latest FAA approved revision), F.S. 69.31 bulkhead assembly. ST-UN-M002, Item 5-3 bulkhead inspection. NOTE: References are for manufacturer’s use only.Issued: September 26, 2013 Revised: November 6, 2013 226-53-017 R1 Page 3 of 8 

# SERVICE BULLETIN SA226 SERIES

K. Other Publications Affected: SA226/227 Series Structural Repair Manual (SRM). ST-UN-M002 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. 69.31: 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 per SA226/227 Structural Repair Manual (SRM), chapter 51-30-02. D. Perform a Detail Visual Inspection (DVI) of the F.S. 69.31 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) or SRM instructions. H. If no cracking is found, it is permissible to reseal per SRM 51-30-03 (pressure boundary).Issued: September 26, 2013 Revised: November 6, 2013 226-53-017 R1 Page 4 of 8 

# SERVICE BULLETIN SA226 SERIES

I. Reassemble/reinstall all equipment/liners/insulation removed in step B. per applicable sections of the SA226 Maintenance Manual. J. Remove all placards from Battery and External Power switches and reconnect power to aircraft. K. Perform functional/operational checks on all systems that were disturbed per SA226 Maintenance Manual. L. Complete aircraft records in accordance with 14 CFR 43.9. M. Complete and return service bulletin compliance form to M7 AerospaceIssued: September 26, 2013 Revised: November 6, 2013 226-53-017 R1 Page 5 of 8 

# SERVICE BULLETIN SA226 SERIES

FIGURE 1 FS 69.31 FWD PRESSURE BULKHEAD (27-21028) 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 AFTIssued: September 26, 2013 Revised: November 6, 2013 226-53-017 R1 Page 6 of 8 

# SERVICE BULLETIN SA226 SERIES

FIGURE 2 RHS VIEW OF BULKHEAD WITH CRACKS NOTED (VIEW LOOKING AFT INSIDE FWD BAGGAGE COMPARTMENT) Stringer 8

Stringer 9Issued: September 26, 2013 Revised: November 6, 2013 226-53-017 R1 Page 7 of 8 

# SERVICE BULLETIN SA226 SERIES

FIGURE 3 LHS VIEW OF BULKHEAD WITH CRACKS NOTED (VIEW LOOKING AFT INSIDE FWD BAGGAGE COMPARTMENT) Stringer 9Issued: September 26, 2013 Revised: November 6, 2013 226-53-017 R1 Page 8 of 8 

# SERVICE BULLETIN SA226 SERIES

FIGURE 4 TYPICAL CRACK LOCATION (VIEW WITH EXTERNAL FUSLAGE SKIN REMOVED) CRACK

### SERVICE BULLETIN COMPLIANCE FORM
226-53-017 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.
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Bulletin Issue Date Revision Date Aircraft Registration Number Operator/Owner

Time on Aircraft Date Accomplished
CommentsM7 AEROSPACE LP P. O. BOX 790490 SAN ANTONIO, TEXAS 78279–0490

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