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 Bulletin 227-53-009, 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) 824–9421
CHAPTER 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 and

Right Hand Forward Wingto-Body Attach Fittings
CHAPTER 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 Cracks
Issued: 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 Drawing 27K24191, 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 Inspection

Inspect 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 approximately

8X magnification or greater, examine those surface details specified in the inspection requirements noting defects as directed by the inspection requirements.

Close Visual Inspection

Inspect 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 aforementioned

inspection 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 the
Issued: 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.

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Issued: 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).

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Issued: 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

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Issued: 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 corner
Issued: 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 at MetroTech@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. If
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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 and

no 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 Validity
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SERVICE BULLETIN

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(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.
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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

D R NOITPIRCSE P Y EBMUNTRA TQ

K 1 **ti 2 1 00-39142K7

H g *erawdra S R niwarDtiKee /A
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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 OPENING
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SERVICE BULLETIN

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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)
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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. 133.873
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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 AREAS
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SERVICE BULLETIN

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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

FWD
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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

TYPICAL
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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 3
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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
SERVICE BULLETIN COMPLIANCE FORM

227-53-009

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
M7 AEROSPACE LP

P. O. BOX 790490

SAN ANTONIO, TEXAS 78279–0490

(Staple)

ATTN: Service Engineering Department

Fold Here to Mail

Fold Here to Mail

Place

Stamp

Here