P.O. Box 790490 • San Antonio, Texas 78279–0490 • (210) 824–9421 TO: HOLDERS OF SA227 SERIES SERVICE INFORMATION MANUALS

Attached is SA227 Series Service Bulletin227-53-009,Inspection, Extended Inspection, and Repair of Fuselage Upper Forward Corner of Main Cabin Door Cutout, Issued:November 15, 2013. On aircraft with a bayonet shear pin main cabin door latching mechanism (as opposed to a "click-clack" latching mechanism), the internal door surround doubler, the external skin fuselage skin and, in some cases, the door corner fitting have been found cracked at the fuselage upper forward corner of the main cabin door cutout. Please insert the attached revised Chapter 53 Index pages.P.O. Box 790490 • San Antonio, Texas 78279–0490 • (210) 824–9421CHAPTER 53 – FUSELAGE SA227 SERIES INDEX

Issued: March 30, 1982 Revised: November 15, 2013 CHAPTER 53 INDEX Page 1 of 2 NUMBER DATE TITLE AIRCRAFT EFFECTIVITY 53-001 03-30-82 Fuselage - Radome SA227-TT, S/N TT421-503, SA227-AC, S/N AC420-505, SA227-AT, S/N AT423-504. 53-002 02-23-84 Inspection and/or SA227-TT, S/N TT421-555, (R) 03-29-84 Repair Fuselage Skin SA227-AC, S/N AC406, 415, Cracks 416, 420-599, SA227-AT, S/N AT423-597. 53-003 01-29-86 Inspection/Beef- SA227-AT, S/N AT423-469, (R) 02-13-86 Up Cargo Door Area SA227-AC, S/N AC406, 415, Belt Frames 416, 420-478, except AC457 and AC470.
53-004 01-18-93 Cabin Entrance Door SA227-TT, S/N TT421-541, Sill Beef Up SA227-AT, S/N AT423- 695, SA227-AC, S/N AC 406, 415, 416, 420-789. SA227-BC, S/N BC420-789. 53-005 09-22-94 Cockpit Floorboard FOD All SA227 Series Airplanes (R)06-05-96 Barrier Installation 53-006 11-07-07 Radome Lightning All SA227 Series Airplanes Protection 53-007 09-03-10 Installation of Form-in-Place All SA227 Series Airplanes Gaskets - Wing-to-Body Fairings 53-008 10-08-10 Access Panels Installation All SA227 Series Airplanes (R)01-26-11 53-009 11-15-13 Inspection, Extended All SA227 Series Airplanes Inspection, and repair of Fuselage Upper Forward Corner of Main Cabin Door Cutout 53-010 07-27-12 Inspection and/or Replace- All SA227 Series Airplanes (R)05-13-13 ment of the Left Hand andRight Hand Forward Wingto-Body Attach FittingsCHAPTER 53 – FUSELAGE SA227 SERIES INDEX

NUMBER DATE TITLE AIRCRAFT EFFECTIVITY

Issued: March 30, 1982 Revised: November 15, 2013 CHAPTER 53 INDEX Page 2 of 2 53-011 09-26-13 Inspection of F.S. 69.31 All SA227 Series Airplanes (R)11-06-13 Forward Pressure Bulkhead for CracksIssued: November 15, 2013 227-53-009 Page 1 of 22 

# SERVICE BULLETIN SA227 SERIES



### FUSELAGE Inspection, Extended Inspection, and Repair of Fuselage Upper Forward Corner of the Main Cabin Door Cutout
1. PLANNING INFORMATION A. Effectivity: Merlin IVC, SA227-AT, SN AT570-AT631, AT695 Metro III, SA227-AC, SN AC570-AC788 Metro III, SA227-BC, SN BC762, BC764, BC766, BC770-BC789 This service bulletin applies only to aircraft using a bayonet shear pin type of latching mechanism for the main cabin door. If aircraft listed in Step 1.A. use click-clack fittings, this inspection does not apply. (See Figure 3 for typical click-clack and bayonet style fittings)
B. Reason: On aircraft, identified above, with a bayonet shear pin main cabin door latching mechanism (as opposed to a "click-clack" latching mechanism), the internal door surround doubler, the external skin fuselage skin and, in some cases, the door corner fitting have been found cracked at the fuselage upper forward corner of the main cabin door cutout. C. Description: Inspect internal or external skin doubler, fuselage skin, and fuselage door frame corner member for cracking. If cracks are found, repair steps are included in this bulletin. If cracks are not found, the repair doubler or tripler can still be added extending the inspection intervals. D. Compliance: Mandatory The following initial interval is specified. This interval assumes that the repair members specified by this bulletin have not been installed. For aircraft with more than 35,000 Total Aircraft Cycles (TAC), inspect within the next 300 cycles or 2 calendar months, whichever occurs first, from the date of this service bulletin. For aircraft with 20,001 - 35,000 TAC, inspect within the next 600 cycles or 4 calendar months, whichever occurs first, from the date of this service bulletin.Issued: November 15, 2013 227-53-009 Page 2 of 22 

# SERVICE BULLETIN SA227 SERIES

For aircraft with 12,000 - 20,000 TAC, inspect within the next 1,000 cycles or 12 calendar months, whichever occurs first, from the date of this service bulletin. For aircraft with less than 12,000 TAC, inspect at 12,000 cycles or within the next 1,000 cycles, whichever occurs later. Repeat inspection interval for all aircraft is also required. Inspection Requirements: Refer to step 2.A. for details. E. Approval: FAA Approved for Engineering Design. F. Manpower: M7 Aerospace estimates the following manhours per aircraft to accomplish the inspections: (1) HFEC/LFEC/Detail Visual Inspection - 2.5 hours for threshold inspection. (2) LFEC with Detail Visual Inspection - 2.0 hours for repeat inspection with inner doubler cracked. (3) HFEC with Detail Visual Inspection - 1.5 hours for repeat inspection with intact inner doubler (4) Installation of repair - 48 hours. 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: Contact M7 Aerospace for price and availability. See Step 8. for Material Listing. Orders need to be placed with M7 Aerospace as there is a lead time on some parts. H. Tooling – Price and Availability: The NDT calibration standards (27-02171-001 and 27-02171-021) identified in the Material Listing, Table 4, are the only specialized tools. The standard, P/N 27- 02171-001, is supplied by M7 Aerospace in the bulletin kit or it can be purchased separately from M7 Aerospace. The P/N 27-02171-021 standard will be available from M7 Aerospace at a later date. Contact M7 Aerospace for price and availability.Issued: November 15, 2013 227-53-009 Page 3 of 22 

# SERVICE BULLETIN SA227 SERIES

I. Weight and Balance: (1) For inspections only - None. (2) For installation of the repair kit (P/N 27K24191-001) - 2.5 lbs at F.S. 151. For installation of skin repair per 27K24191-003, 1.0 lbs at F.S. 130. Update the AFM Weight and Balance data. J. References: M7 Engineering Drawing27K24191, Rev B (or latest FAA approved revision) M7 M-5420 Memorandum M7 Report R1987 - HFEC and LFEC Inspection of Inner Doubler. M7 Report R2027 - LFEC Inspection of Fuselage Skin. M7 Aerospace Report No. M07-012-002(latest FAA approved revision) M7 Aerospace Report No. M07-013-002(latest FAA approved revision)
NOTE:References are for manufacturer’s use only. K. Other Publications Affected: ST-UN-M001
2.ACCOMPLISHMENT INSTRUCTIONS This bulletin contains inspections and modifications based upon three scenarios. Table 1 outlines the basic inspection of this bulletin when complying with the inspection for the first time. Repeat inspections continue if no cracking is found. Table 2 outlines the new inspections that must be performed once the repair members for the kit repair are installed. Installation of the kit does not remove all of the Table 1 inspections. Several of the Table 1 inspections carry over even when the repair members are installed. Table 3 offers an option to the operator. It permits the operator to install the repair members as a preventative measure when no cracking is observed after the first threshold inspection. These members can be installed at any time after the threshold inspection or follow up repeat inspections. In many cases, the addition of the repair members to uncracked structure will result in a new threshold inspection AFTER the aircraft is retired. Each table identifies figures and bulletin steps detailing the specific inspections to be performed. It is recommended the operator review the entire bulletin for all applicability. Each table has several specific notes listed below the table as well as the general notes that follow this paragraph below.Issued: November 15, 2013 227-53-009 Page 4 of 22 

# SERVICE BULLETIN SA227 SERIES

NOTES: The expected aircraft configuration for this service bulletin installation is: No existing repairs are installed or have been performed at this upper forward door surround corner. If this is not the case and repairs are installed at this location, refer to step 7. Some aircraft between serial numbers AT/AC 570 and AT/AC 601 have a factory fitted external skin doubler rather than an internal doubler. The inspection is clarified for these aircraft. See step 2.H. If any of the remaining three corners of the door cutout have a repair or kit drawing modification installed, this is accommodated within the inspections specified by this bulletin. See step 2.G. Definition of Inspections identified in this step: Detailed Visual InspectionInspect using an illumination device (such as circular flourescent 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 approximately8X magnification or greater, examine those surface details specified in the inspection requirements noting defects as directed by the inspection requirements. Close Visual InspectionInspect using an illumination device (such as circular flourescent inspection luminaire) which produces a minimum of 100 fc of light intensity at the part surface and a magnification device (such as the integral magnifier of the aforementionedinspection luminaire) producing approximately 1.5X magnification or greater, examine all surface details of the part noting any obvious defects. Sub-Surface Inspection - HFEC/LFEC A subsurface inspection requires calibration. See M7 Aerospace Report R1987 for inspection procedure and calibration standard (27-02171-001). Both are included in the kit. Both High Frequency Eddy Current (HFEC) and Low Frequency Eddy Current (LFEC) are classed as subsurface inspections. Report R2027, which addresses inspection of the repair members once installed, is not ready at the time of this bulletin release. Contact M7 Aerospace for a copy when needed. A. Perform the Threshold (Initial) and Repeat inspection outlined in Table 1: (1) when complying with this bulletin for the first time per step 1.D. or (2) continuing the repeat inspections as no cracks have been found and theIssued: November 15, 2013 227-53-009 Page 5 of 22 

# SERVICE BULLETIN SA227 SERIES

operator has elected not to install the repair members per step 6. These inspections still apply if 27K24191-003 skin repair installation is performed.

NOTES: <0> Perform these specific service bulletin steps. <1> Repeat inspection interval assuming no damage or defects found. <2> This inspection is applicable to aircraft S/N AT/AC 570 thru AT/AC 601 only due to existing factory installed skin doubler prior to this service bulletin. TABLE 1 INITIAL INSPECTION

(1) If threshold inspection determines there is an existing repair in the upper forward corner of the door surround, proceed to step 7. (2) If crack(s)/damage is found during inspection, go to steps 3., 4., and/or 5. as applicable depending on component cracked/damaged. Use step 2.B. and Table 2 for future inspection criteria when repair kit members (27K24191-001) are installed. Use Table 1 inspection intervals if only skin or corner fitting were cracked and replaced and no repair doubler is installed. If only skin and fitting were replaced, it is permissible to install kit per step 6. (3) If no defect/damage is found, proceed to step 2.I. for aircraft close up or to step 6. when choosing to extend repeat inspection interval. B. Perform the Threshold and Repeat Inspection outlined in Table 2 when cracks are found following either the threshold or repeat inspection in Table 1. These inspections are based on the 27K24191-001 repair members being installed. NOITCEPSNI

NOITACOL NOITCEPSNI DOHTEM/EPYT PETSLIATED >0< ERUGI F D LOHSERHT

)SELCYC( TAEPER )SELCYC( >1<
tarelbuodrennI dwFreppU ,renroC ,nikSegalesuF renroCdna gnittiF ,lausiVliateD CEFL,CEFH dnalanretxE( lanretnI )snoitcepsnI ,.E.2,.D.2 )1(.F.2 5, 4 0 00,2 1 0 00,2

nikSlanretxE relbuoD >2< lausiVliateD dnalanretxE( )lanretnI .H. 2 6 0 00,2 1 0 00,2

fosrenroCrehtO tuotuCegalesuF lausiVesolC dnalanretxE( )lanretnI .G. 2 7 0 00,21 000,2Issued: November 15, 2013 227-53-009 Page 6 of 22 

# SERVICE BULLETIN SA227 SERIES

NOTES: <0> Perform these specific service bulletin steps. <1> The Table 2 threshold inspection cycles start after the repair doubler in step 3. is installed. <2> The Table 2 repeat inspection follows the Table 2 threshold inspection once the repair members are installed. <3> Continuation of Table 1 repeat inspection on the other three corners of the cutout if no cracks were found. TABLE 2 INSPECTION - CRACKED INNER DOUBLER REPAIRED (P/N 27K24191 KIT INSTALLED)

Maintain this inspection criteria for the duration of the aircraft life. Proceed to step 2.I. for close up. C. Perform Threshold and Repeat Inspection outlined in Table 3 when the 27K24191-001 repair members have been installed as a preventative measure per step 6. These inspections assume no cracks exist and that the fuselage skin Inner Doubler is fully intact (has not been repaired). NOITCEPSNI

NOITACOL NOITCEPSNI DOHTEM/EPYT PETSLIATED >0< ERUGI F D LOHSERHT

)SELCYC( TAEPER )SELCYC(

tanikSegalesuF drawroFreppU renroC CEFL )lanretxE( )2(.F. 2 5 > 1<000,5 1 > 2<000,2

riapeRlanretxE tarelbuoD drawroFreppU renroC lausiVliateD )lanretxE( )1(.D. 2 4 >1<000,5 1 > 2<000,2

riapeRlanretxE tarelbuoD drawroFreppU renroC lausiVliateD )lanretnI( )3(.D. 2 8 >1<000,0 3 > 2<000,6

fosrenroCrehtO tuotuCegalesuF lausiVesolC dnalanretxE( )lanretnI .G. 2 7 A / N > 3<000,2Issued: November 15, 2013 227-53-009 Page 7 of 22 

# SERVICE BULLETIN SA227 SERIES

NOTES: <0> Perform these specific service bulletin steps. <1> The Table 3 threshold inspection cycles start after the repair members per step 3. are installed. <2> The Table 3 repeat inspection follows the Table 3 threshold inspection. <3> Continuation of Table 1 repeat inspection on the other three corners of the cutout if no cracks were found. <4> An option is available to perform inspection at 20,000 cycles threshold and 6,000 cycles recurring or 30,000 cycles threshold and 3,000 cycles recurring. The operator can select which option is better suited to their existing maintenance schedule. TABLE 3 INSPECTION - INNER DOUBLER NOT CRACKED -

PREVENTATIVE P/N 27K24191 KIT INSTALLED This option allows the operator to install the repair kit per step 6. even though no damage/defect was found after the first initial inspection called out in step 1.D. It extends the next inspection for the forward upper corner from a repeat of every 2,000 cycles to a new threshold of 20,000 cycles (see Note <4>). The other three corners still require repeat 2,000 hour inspections per step 2.G. Once the kit is installed, proceed to step 2.I. for close up instructions. D. Detail Visual Inspection (DVI) (See Figure 4) (1) External Inspection Prepare the surface for inspection in accordance with SA226/227 Structural Repair Manual (SRM), Chapter 51-30-07. It is not required to remove surface finish (paint) to perform this inspection. If compounds such as Devcon F or NOITCEPSNI

NOITACOL NOITCEPSNI DOHTEM/EPYT PETSLIATED >0< ERUGI F D LOHSERHT

)SELCYC( TAEPER )SELCYC(

nikSrennI tarelbuoD drawroFreppU renroC CEFH )lanretxE( .E. 2 5 >2<000,3>1<000,03

RO>4<
>2<000,6>1<000,02 fosrenroCrehtO tuotuCegalesuF lausiVesolC dnalanretxE( )lanretnI .G. 2 7 A /N >3<000,2Issued: November 15, 2013 227-53-009 Page 8 of 22 

# SERVICE BULLETIN SA227 SERIES

liquid shim are present, which hinder a detail visual inspection, then these compounds must be removed. Care is required not to remove any base material of the surface being cleaned. Perform a detail visual inspection (as defined in step 2) of the forward upper skin corner fitting, and the visible edge of the inner doubler of the passenger door cutout at the interval specified in Table 1. Perform this same inspection on the corner fitting, edge of fuselage skin, repair doubler and tripler once the 27K24191 repair kit has been installed. Inspect for cracks or pulled/loose fasteners. (2) Internal Inspection (Kit 27K24191-001 repair members not installed) Gain access to the interior side of the fuselage skin structure immediately adjacent to the upper forward corner of the door cutout. This may require removal of the cabin liner, any interior bulkheads, or cabin furnishings/ monuments. Refer to SA227 Illustrated Parts Catalog (IPC), Chapter 25 for components, and SA227 Maintenance Manual, Chapter 25 for access. Retain all hardware. Prepare surface for inspection in accordance with SA226/227 Structural Repair Manual (SRM), Chapter 51-30-07. Perform a detail visual inspection (as defined in step 2) of the inner skin doubler only, around the fasteners shown in the shaded region of Figure 4, at the interval specified in Table 1. It is not required to remove surface finish (paint/ primer) to perform this inspection. Several fasteners in the actual corner are not visible due to a gusset blocking the view. It is not required to remove the gusset. (3) Internal Inspection (Kit 27K24191-001 repair members installed) Gain access to the interior side of the fuselage skin structure immediately adjacent to the upper forward corner of the door cutout. This may require removal of the cabin liner, any interior bulkheads, or cabin furnishings/ monuments. Refer to SA227 Illustrated Parts Catalog (IPC), Chapter 25 for components, and SA227 Maintenance Manual, Chapter 25 for access. Retain all hardware as required. Prepare the surface for inspection in accordance with SA226/227 Structural Repair Manual (SRM), chapter 51-30-07. Perform a Detailed Visual Inspection (DVI), as defined in step 2, of the fuselage skin surface immediately at the peripheral row of fasteners attaching the external repair doubler to the structure underneath (see Figure 8), at the interval specified in Table 2. It is not required to remove any surface finish (paint/primer) to perform this inspection. Several fasteners in the actual cornerIssued: November 15, 2013 227-53-009 Page 9 of 22 

# SERVICE BULLETIN SA227 SERIES

are not visible due to a gusset blocking the view. It is not required to remove this gusset. Inspection is centered on cracking of the fuselage skin and loose/ damaged fasteners. E. High Frequency Eddy Current (HFEC) Inspection of Inner Doubler Edge (1) Gain access to exterior edge of the inner doubler at the upper forward corner of the cutout. Remove any Devcon F or liquid shim material to clearly see the edge. Perform the inspection in accordance with Kit Report R1987 (NDT Eddy Current Inspection procedure), HFEC inspection. The inner doubler and fuselage skin edges are flush with each other. (See Figure 5) F. Low Frequency Eddy Current (LFEC) Inspection of Inner Doubler and Fuselage Skin (1) Inner Doubler: Gain access to exterior surface of the fuselage skin at the upper forward corner of the cutout immediately around the two rivets as indicated in Figure 1. Perform the inspection in accordance with Kit Report R1987 (NDT Eddy Current Inspection procedure), LFEC inspection. This inspects for cracks emanating around the two rivets, shown in Figures 1 and 5, in the inner doubler.(2) Fuselage Skin: When performing this inspection after the 27K24191 kit members have been installed, the LFEC inspection now inspects the skin with the probe placed on the tripler surface. Perform inspection using procedure R2027. Gain access to exterior surface of the tripler at the upper forward corner of the door cutout. Perform the inspection around the same two rivets shown in Figure 5. G. Close Visual Inspection of Other Cutout Corners (1) Applicable to the fuselage skin at lower forward and aft corners and aft upper corner of the door cutout for the passenger door. (See Figure 7) (2) Gain access to the exterior fuselage skin around the three corners. If an external doubler (whether by previous repair or installed by modification kit) is installed at any of these three corners, perform the Close Visual Inspection of the external doubler, the skin, and all fastener locations common to both. No paint/finish is required to be removed to perform this inspection. (3) Gain access to the interior of the fuselage skin/inner doubler around the three corners. (a) This may require removal of interior components such as interior bulkheads, monuments, seating etc. as well as interior side panels. All hardware shall be retained unless it is required to be replaced. No paint/finish is required to be removed to perform this inspection.Issued: November 15, 2013 227-53-009 Page 10 of 22 

# SERVICE BULLETIN SA227 SERIES

(b) Perform a close visual inspection of the inner doubler, adjacent skin, and all visible fasteners common to both. (4) Once the inspection is complete, the interior components may be reinstalled. H. Detail Visual Inspection of External Skin Doubler. (1) Applicable to the aircraft with S/N AT/AC 570 thru AT/AC 601 only fitted with the factory installed external skin doubler around the entire periphery of the door cutout for the passenger door. Some aircraft in this range do not have the external doubler nor door bayonet type fittings so this inspection (entire bulletin) DOES NOT apply. (a) Obtain access to the exterior fuselage doubler. (b) Prepare the surface for inspection per SA226/227 Structural Repair Manual (SRM) 51-30-07. It is not necessary to remove surface finish (paint) to perform this inspection. Remove compounds such as Devcon F or liquid shim that prevent detail visual inspection. Take care not to remove any base material of the surface being cleaned. (2) Perform the Detail Visual Inspection (DVI) of the external doubler and the edge of the fuselage skin (see Figure 6), all fasteners common to both, looking for signs of cracking. Perform a DVI of the corner fitting looking for any signs of cracking. (3) Obtain access to the interior of the fuselage skin immediately around the upper forward corner. (a) This may require removal of interior components such as interior bulkheads, monuments, seating, etc. as well as interior side panels. Retain all hardware for reinstallation. (b) No paint/finish is required to be removed for this inspection. (c) Perform a Close Visual Inspection of the fuselage skin, and all visible fastener locations attaching the external doubler to the fuselage skin, looking for signs of fasteners distress or cracking emanating from the fasteners in the skin. (4) Once the inspection is complete, the interior components may be reinstalled per the applicable sections of the SA227 Maintenance Manual. (5) If any crack damage is found in the fuselage skin or external doubler following the step 2.H. inspections, report the damage to M7 Aerospace at MetroTech@M7Aerospace.com. M7 Aerospace will provide repair details.Issued: November 15, 2013 227-53-009 Page 11 of 22 

# SERVICE BULLETIN SA227 SERIES

I. Close Up of Aircraft Following Inspection. (1) Following any of the inspections outlined in Tables 1, 2, or 3, the interior of the aircraft can be restored to same condition prior to inspection. Refer to SA227 Maintenance Manual (MM) and SA227 Illustrated Parts Catalog (IPC) for details. (a) Reinstall all interior components using retained hardware. Replace hardware as required. (b) Restore any surface finishes removed to perform inspection per SA226/227 SRM, 51-30-02. (c) Functionally check any systems disturbed as a result of this inspection per applicable sections of the SA227 MM. (2) Following any of the inspections outlined in Tables 1, 2, or 3, restore exterior surface finish of the fuselage skin or edge of inner or external doublers, if required, per SA226/227 SRM 51-30-02. (3) Restore use of Devcon F or liquid shim as previously used prior to inspection for sealing purpose. (4) Functionally check any systems that were disturbed as a result of these inspections in accordance with the applicable sections of SA227 Maintenance Manual.
J. Report all cracks/damage to M7 Aerospace atMetroTech@M7Aerospace.com. Please indicate whether repair was installed due to cracking being found. The FAA has tasked M7 Aerospace to track the extent of the fleet damage. K. Complete aircraft records according to 14 CFR 43.9. L. Complete and mail Service Bulletin compliance form to M7 Aerospace Technical Publications Department.
3. REPAIR OF CRACKED INNER DOUBLER Repair cracked inner skin doubler per inspection in step 2. The installation of the repair members is outlined in M7 Aerospace kit drawing 27K24191 (27K24191-001). The crack damage must be removed prior to installation of repair members in accordance with the following steps: A. Determine the end of the crack. Penetrant or HFEC methods in accordance with SA226/227 Structural Repair Manual (SRM) may be used. B. Trim out the crack in the inner doubler by cutting a slot minimum width 0.25 inch, end radius 0.25 inch to extend at least 0.030 inch past the end of the crack. IfIssued: November 15, 2013 227-53-009 Page 12 of 22 

# SERVICE BULLETIN SA227 SERIES

the crack passes through fasteners. The slot must remove the countersink of each fastener. Maintain 2D edge distance of any remaining fasteners in the inner doubler (see Figure 9). C. Break all sharp edges on the slot cut. D. Confirm crack has been removed by HFEC inspection of slot per SA226/227 Structural Repair Manual (SRM), chapter 51-30-07. E. Alodine and prime edge of slot per SA226/227 Structural Repair Manual (SRM), chapter 51-30-02. F. Fabricate filler for slot using 0.050 inch thick 2024-T3/T42 material with profile to match slot. Ensure filler is smaller than slot with minimum gap 0.030 inch to edge of slot. Alodine and prime filler per SA226/227 Structural Repair Manual (SRM), chapter 51-30-02. G. During installation of repair members 27K24191, locate filler into slot using sealant per SA226/227 Structural Repair Manual (SRM), chapter 51-30-03, picking up existing fastener pattern.
4. REPAIR OF CRACKED FUSELAGE SKIN To repair a cracked exterior fuselage skin found in inspection step 2, follow M7 Aerospace kit drawing 27K24191. If only the skin is cracked and there is no damage to the inner fuselage doubler, the skin can be replaced per kit installation 27K24191-003. If the skin is replaced and no other cracks are present, continue to use the inspections per Table 1. Proceed to step 5 if the corner fitting is cracked, otherwise go to step 2.I. for close up or return to step 2.A.(2) for further instructions.
5. REPAIR OF CRACKED CORNER FITTING Replace the cracked corner fitting found in inspection step 2. If the fitting is replaced andno other cracks are present, continue to use the inspections per Table 1. Refer to ST-UNM001, Item 3-5, and the life limit of corner fitting. Life limit on this part remains in effect, but resets when part is replaced.
6.ADDITION OF KIT DRAWING REPAIR MEMBERS AS PREVENTATIVE ACTION If following the Table 1 Threshold (initial) inspection or any following repeat inspection thereafter, and no defect(s)/damage to the inner doubler, the 27K24191-001 kit may be installed to extend the inspection intervals. For example, if you perform a required inspection per Table 1, the repeat inspection is now every 2,000 cycles thereafter. However, the operator can choose to install the 27K24191-001 repair kit to extend the next inspection out to 30,000 cycles rather than 2,000 cycles. The additional 30,000 cycles, on top of the current aircraft total cycles at the time of modification may exceed the Limit of ValidityIssued: November 15, 2013 227-53-009 Page 13 of 22 

# SERVICE BULLETIN SA227 SERIES

(aircraft life) of 50,000 hours for some operators. Follow the inspection criteria per step 2.C. to extend the inspection with the repair kit installed. This step does not apply to those aircraft fitted with the factory installed external fuselage skin doubler around the periphery of the door cutout.
7. EXISTING REPAIRS ALREADY INSTALLED AT UPPER FORWARD CORNER For the aircraft effectivity listed in step1.A., if a repair already exists, then the existing repair most likely will have to be removed if it does not meet the requirements of this service bulletin kit drawing repair. M7 Aerospace has record of several repairs undertaken by some operators. It is also probable that there are other repairs in the field that need to be replaced. M7 Aerospace will work with the operator in determining the best course of action for these aircraft. Full details of the existing repairs need to be supplied to M7 Aerospace Engineering to determine the acceptability of the repair. All details including photos, sketches, fuselage station numbers, BL (buttline) numbers, etc. need to be sent to MetroTech@M7Aerospace.com or faxed to 210-820-8626. In lieu of contacting M7 Aerospace with existing repair information, the operator may wish to replace the existing repair with the service bulletin kit repair, providing the installation is per the kit repair requirements. Following installation, the step 2.C. inspection criteria are applicable. Lastly, several aircraft with serial numbers less than AT602, AC602 have a factory fitted external doubler kit. Unless cracking is found, this installation does not require removal. Inspections per step 2.G. shall apply to all four (4) corners for these aircraft.Issued: November 15, 2013 227-53-009 Page 14 of 22 

# SERVICE BULLETIN SA227 SERIES

8. MATERIAL LISTING

* Customer Supplied Material ** Only M7 Aerospace supplied kit, including specific part numbers used in the kit, show compliance with the parts needed for repair. Any alternate parts not bearing the M7 Aerospace part number and QA stamp requires approval by M7 Aerospace. This kit contains the repair kit 27K24191 members, calibration standard, NDT procedure R1987 and repair drawing 27K24191. Another kit is being developed to contain the LFEC calibration standard and the NDT procedure R2027 required for step 2.F.(2). It is currently not available.

TABLE 4 

## NOITPIRCSE D R EBMUNTRA P Y TQ

**ti K 1 00-39142K7 2 1

*erawdra H g niwarDtiKee S R /AIssued: November 15, 2013 227-53-009 Page 15 of 22 

# SERVICE BULLETIN SA227 SERIES

FUSELAGE SKIN

DOOR CORNER FITTING INDICATION OF CRACK IN INTERNAL DOUBLER, ADJACENT TO RIVET INTERNAL DOUBLER 

### Probable cracks in fuselage skin or external doubler (extending out from 2 rivets shown) (Door Opening) UP

FWD F.S. 126.06 F.S. 133.873

FIGURE 1 VIEW LOOKING INBOARD AT UPPER FWD DOOR OPENING CORNER FITTING

FIGURE 2 VIEW LOOKING AT EDGE OF FUSELAGE DOOR OPENINGIssued: November 15, 2013 227-53-009 Page 16 of 22 

# SERVICE BULLETIN SA227 SERIES



### DOOR FRAME 

## OR 

# A CLICK-CLACK

BAYONET

FIGURE 3

CLICK-CLACK AND BAYONET LATCHES (DETAIL A - VIEW SHOWING BAYONET INSTALLED, BUT CLICK-CLACKS ARE INSTALLED ON EARLIER SERIAL NUMBERS)Issued: November 15, 2013 227-53-009 Page 17 of 22 

# SERVICE BULLETIN SA227 SERIES

FIGURE 4 DETAIL VISUAL INSPECTION AREA OF EXTERNAL SKIN, EDGE OF INNER DOUBLER AND CORNER FITTING (SHADED ZONE) 

## (Door Opening) UP

FWD F.S. 126.06 F.S. 133.873Issued: November 15, 2013 227-53-009 Page 18 of 22 

# SERVICE BULLETIN SA227 SERIES

UP

FWD F.S. 133.873 LFEC Inspection around these 2 rivets

Edge of outer skin, flush with edge of Inner Doubler HFEC Inspection of Inner Doubler Edge. Corner Fitting 2.0” 2.0”

FIGURE 5 HFEC AND LFEC INSPECTION AREASIssued: November 15, 2013 227-53-009 Page 19 of 22 

# SERVICE BULLETIN SA227 SERIES

FIGURE 6 EXTERNAL SKIN DOUBLER - EXTERNAL INSPECTION (INSPECT INTERIOR OF SIMILAR SHADED AREA AND SAME LOCATION) (Door Opening) Edge of External Doubler, shown flush with skin.

Inspect edge of external Doubler and fuse skin along this length. Outline of external Kit Doubler

Inspection Area shaded (defined by dimensions shown.) UP

FWD F.S. 126.06 F.S. 133.873 F.S. 139

2.0”

2.0” Probable cracks in fuselage skin or external doubler (extending out from 2 rivets shown) UP

FWDIssued: November 15, 2013 227-53-009 Page 20 of 22 

# SERVICE BULLETIN SA227 SERIES

FIGURE 7 INSPECTION OF OTHER CORNERS OF FUSELAGE CUTOUT (INSPECT INTERNAL STRUCTURE IN SAME AREA AND LOCATION) (SHADED REGION TO BE INSPECTED) VIEW LOOKING INBOARD AT PASSENGER DOOR OPENING OUTLINE OF INTERNAL PRODUCTION DOUBLER

TYPICALIssued: November 15, 2013 227-53-009 Page 21 of 22 

# SERVICE BULLETIN SA227 SERIES

FIGURE 8 INTERNAL INSPECTION OF PERIPHERAL ROW OF FASTENERS ATTACHING REPAIR DOUBLER (27K24191-001) CANOPY

STRINGER 4

27-24202-001 EXTERNAL DOUBLER 27-24202-003 EXTERNAL DOUBLER

.31 TYP BL 0.00 FS 126.06

REF 27-22047 HEADER

REF 27-24083 CORNER

UP

FWD INSPECT FASTENERS AND INNER SURFACE OF FUSELAGE SKIN IN SHADED AREAS STRINGER 5

WINDSHIELD

REF WINDSHIELD SCREWS FS 133-873
REF 27-22126 FRAME ASSY

REF 27-20060 INTERNAL GUSSET

STRINGER 1

REF 27-22215 INTERNAL DOUBLER FS 144.247

FS (147.17) FS (145.95) FS 148.00 FS 145.12 STRINGER 2

STRINGER 3Issued: November 15, 2013 227-53-009 Page 22 of 22 

# SERVICE BULLETIN SA227 SERIES

FIGURE 9 CRACK REMOVED BY SLOT TRIMMING (Door Opening)

Probable cracks in inner doubler (extending out from 2 rivets shown)

Cut slot in Inner Doubler to remove crack with min 0.25 inch radius at end of crack. Ensure 2D on remaining Inner Doubler fasteners. If crack passes through rivets, ensure slot is wide enough to just remove the countersink in the Inner Doubler. UP

FWD F.S. 126.06 F.S. 133.873

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