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Service Bulletin 241 September 26, 2012 

FUSELAGE ATTACHMENT TO WING MAIN SPAR - INSPECTION & REINFORCEMENT 

EFFECTIVITY: MODELS SERIAL NUMBERS 

 690 All (except S/N 11057) 

 690A All (except S/N 11104, 11106, 11129, 11134, 11146, 11159, 11173, 

11192, 11220, 11237, 11252, 11263, 11280, 11287, 11298, 11303, 

11317, 11339 & 11341) 

 690B All (except S/N 11383, 11384, 11401 & 11436) 

Note: Aircraft serial numbers configured with AVIADESIGN, Inc. STC No. SA5740NM are not compatible with the 

modifications contained in SB 241. These aircraft will require FAA approved Alternate Methods of Compliance or 

other approved methods to satisfy the structural intent of SB 241. 

REASON FOR PUBLICATION:

Aircraft have been found with cracks in the outer fuselage frame attachment to the lower wing main spar at 

F.S. 178.81 vertical channel (310384-65 LH & -125 RH). Additional damage has been found at the upper picture 

window channel (310704-1 LH & -2 RH), shear clip (310412-23 LH & -24 RH), aft cabin pressure web 

(310384-159), external wing to fuselage fillet (110151-33 LH -34 RH) and working or sheared fasteners. 
SERVICE BULLETIN 241

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COMPLIANCE:

This Service Bulletin contains multiple initial compliance schedules based on the current airframe hours / time-inservice. Part I and II inspections / modifications are required before the expiration of the time period set forth in 

Table A applicable to the airplane; however it is highly recommended that Part I & II, inspections / modifications 

be accomplished at the earliest practicable time. 

INITIAL COMPLIANCE SCHEDULE

CURRENT AIRFRAME 

(HOURS / TIME-IN-SERVICE)

COMPLIANCE REQUIRED PRIOR TO (HOURS / TIS) 

OR WITHIN THE NEXT [MONTHS] WHICHEVER COMES FIRST

0000 - 2000 

2001 - 3000 

3001 - 4000 

4001 - 5000 

5001 - 6000 

6001 - 7000 

Over 7000 

(1000) Hours or [36] Months 

(800) Hours or [36] Months 

(650) Hours or [33] Months 

(500) Hours or [30] Months 

(350) Hours or [24] Months 

(250) Hours or [18] Months 

(150) Hours or [12] Months 

- Table A - 

Part I: ACCESS, DISASSEMBLY & INSPECTION OF THE FUSELAGE TO WING MAIN SPAR 

ATTACHMENT JOINTS

Part I, Access, Disassembly & Inspections are accomplished to record material discrepancies (damage) in the 

fuselage to wing attachment area. Due to amount of man hours required to accomplish Part I, Part II is 

Mandatory. This will eliminate the requirement for future reoccurring inspections. The reinforcements designed 

and installed per this bulletin are terminating action. 

Part II: MODIFICATION AND REASSEMBLY OF THE FUSELAGE TO WING MAIN SPAR ATTACHMENT 

JOINTS

This modification removes all the damaged or potential damaged sheet metal parts in the area of the fuselage to 

wing main spar joint. This modification primarily replaces joint parts with improved heavier machined parts. The 

modification cuts and removes the upper 18.5-inch section of the existing 310384-65/-125 channels and 

incorporates a heavier gage extruded channel as a replacement. The extruded channel was designed to nest 

into the lower remaining section of the existing channel. A vertical strap is cradled into the new frames making 

the joint Failsafe and provides improved fastener edge distance. Parts are being replaced for safety of flight to 

repair damage, prevent future damage and improve load paths. 

BY WHOM WORK WILL BE ACCOMPLISHED:

A & P Mechanic (or Equivalent), and an ASNT Level II or III Certified NDT Inspector (or Equivalent) per 

INSPECTION REQUIREMENTS. 

Due to the complexity of the work and potential to damage existing fuselage and wing structure during 

completion of the modification, it is mandatory that at least one member of the team accomplishing this 

task complete Twin Commander Aircraft approved training. Such training is available at the Factory 

Authorized Maintenance Training Provider.

NOTE:

IT IS RECOMMENDED THAT ALL MODIFICATIONS BE COMPLETED ONLY AT AN 

AUTHORIZED TWIN COMMANDER SERVICE CENTER.
SERVICE BULLETIN 241

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APPROVAL:

Modifications described by this Service Bulletin are FAA DER Approved. 

RELATED PUBLICATIONS: 

SB 164 “INSPECTION AND REPLACEMENT OF WING SPAR FILLET SCREWS”. SB 241 incorporates 

applicable portions of the changes defined per SB 164. 

SB 164 EFFECTIVITY: MODELS 690 (S/N 11000 – 11079, except 11011, 11014, 11021, 11028, 

11035, 11041, 11042, 11046, 11058, 11060, 11065, 11069 & 

11074) 

690A (S/N 11100 – 11344, except 11103, 11105, 11111, 11128, 

11134, 11135, 11141, 11155, 11169, 11170, 11173, 11184, 

11188, 11196, 11199, 11207, 11214, 11218, 11220, 11231, 

11257, 11274, 11277, 11281, 11288, 11291, 11298, 11305, 

11318, 11323, 11325 & 11329) 

690B (S/N 11350 – 11566, except 11338, 11355, 11366, 11406 

& subs.) 

SB 208A “INSPECTION FOR WING MAIN SPAR LOWER CAP CORROSION”. Highly recommend SB 208A and 

SB 241 be accomplished at the same time to reduce man hours. Both Service Bulletins require fuel cells and fuel 

cell liners are removed from the center wing fuel tanks. 

SB 223 “WING LEADING EDGE ATTACHMENT INSPECTION AND MODIFICATION”. Recommend SB 223 and 

SB 241 are accomplished at the same time interval. 

CK-144 “LOWER SPAR CAP REPLACEMENT PROCEDURE”. Highly recommend CK-144 per SB 208A, and SB 

241 be accomplished at the same time interval to reduce overall man hours if deemed necessary. The wing lower 

main spar cap, replaced per SB 208A (CK-144), have fasteners that are common to both SB 208A and SB 241. 

Both Service Bulletins require fuel cells and fuel cell liners are removed from the center wing fuel tanks. 

SI-255 “PICTURE WINDOW UPPER CHANNEL INSPECTION”. Aircraft previously configured with the improved 

310704-3/-4 channels will not require replacement per SB 241. 

SL-382 “SEALING CABIN LEAKS IN AIRCRAFT PRESSURIZED TO THE FLOOR”. Recommend SL-382 and 

SB 241 are accomplished at the same time interval. 

ESTIMATED MAN HOURS: (Per Side - For Access, Inspection, Modification and Assembly) 

Part I: 

Access, Disassembly & Inspections LH Side 92 HRS

 RH Side 92 HRS

Part II: 

Modification & Reassembly LH Side 200 HRS

 RH Side 200 HRS

Parts required to comply with this Service Bulletin may be purchased through any TWIN COMMANDER 

FACTORY-AUTHORIZED SERVICE CENTER. Indicate SB 241, aircraft model and factory serial number when 

submitting order. 
SERVICE BULLETIN 241

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PARTS DATA:

KIT SB241 

Qty Part Number Description 

1 K310384 (DWG) AFT PRESS. BLKHD - WING SPAR FRAME ATTACH REINFORCEMENT 

1 310364-3 CHANNEL K310384-501 INSTL, LH 

1 310364-4 CHANNEL K310384-502 INSTL, RH 

1 310364-5 STRAP K310384-501 INSTL, LH 

1 310364-6 STRAP K310384-502 INSTL, RH 

1 310364-7 TEE K310384-501 INSTL, LH 

1 310364-8 TEE K310384-502 INSTL, RH 

1 310364-9 STRAP K310384-501 INSTL, LH 

1 310364-10 STRAP K310384-502 INSTL, RH 

2 310364-11 WEB K310384-501/-502 INSTL, L & RH 

1 310704-3 CHANNEL K310384-501 INSTL, LH 

1 310704-4 CHANNEL K310384-502 INSTL, RH 

1 310736-45 CLIP K310384-501 INSTL, LH 

1 310736-46 CLIP K310384-502 INSTL, RH 

12 170468-5 SHIM K310384 (USE AS REQD.) 

---------- -------------------------- -------------------------------- --------------------------------------------------------------- 

2 310364-13 FILLER K310384-503/-504 INSTL, L & RH 

2 310364-15 FILLER K310384-503/-504 INSTL, L & RH 

1 310364-17 ANGLE K310384-503 INSTL, LH 

1 310364-18 ANGLE K310384-504 INSTL, RH 

2 310364-19 STRAP K310384-503/-504 INSTL, L & RH 

---------- -------------------------- -------------------------------- --------------------------------------------------------------- 

1 310364-21 DOUBLER K310384-505 INSTL, LH 

1 310364-22 DOUBLER K310384-506 INSTL, RH 

2 310364-23 ANGLE K310384-505/-506 INSTL, L & RH 

1 310364-25 DOOR K310384-505 INSTL, LH 

1 310364-26 DOOR K310384-506 INSTL, RH 

---------- -------------------------- -------------------------------- --------------------------------------------------------------- 

ALL PER DWG HARDWARE 

TO BE PROCURED LOCALLY: (as required) 

1. MS20426AD4, AD5 & AD6 (BB) type rivets and MS20470AD4, AD5 & AD6 (BJ) type rivets. 

2. NAS1097AD5 & AD6 (LZ) type rivets. 

3. NAS1097E5 or KE5 type rivets. 

4. CR3242-4 & -5 (ARD) type rivets and CR3243-4 & -5 (ARE) type rivets. 

5. Epoxy primer used for touch up on parts furnished with the factory Modification Kits per MIL-PRF-23377, Type 

I, Class C. 

6. PR-1440-C20 or PRO SEAL 890-C20 sealant per MIL-S-8802 / AMS-S-8802. 

7. PolyGone 300-AG Gel (Aviation Grade Polysulfide Emulsifier). High performance gel form designed to 

remove polysulfide and other sealants from a variety of surfaces. Follow manufactures recommendations for 

applicable uses of this product 

8. Nashua 345, 3M 474 or Polyken 231, premium grade tape per ASTM D-5486 Type IV, Class 1. 

CAUTION: 

THE SUBSTITUTION OF BLIND RIVETS OTHER THAN THOSE INDICATED ON TWIN COMMANDER 

DWG NO. K310384 IN THE GENERAL NOTES OR ON THE FIELD OF DRAWING IS NOT PERMITTED 

WITHOUT AUTHORIZATION FROM THE AIRFRAME MANUFACTURE OR APPROVED BY A 

REPRESENTATIVE OF THE FAA. 
SERVICE BULLETIN 241

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RECOMMENDED TOOLS:

1. GO-NO-GO gages for HI-LOK fastener inspection. 

2. Sheet metal tools needed for difficult access areas. 

3. Cherry 269C3 selector gage for determining material thickness for installation of blind fasteners. 

4. Cratex rub block stick for cleaning and polishing fastener holes and metal surfaces. 

SPECIAL TOOLS: 

None 

GENERAL INSPECTION CRITERIA:

TYPES OF INSPECTION FOUND IN THIS SERVICE BULLETIN ARE PER AC 43.13-1B CHAPTER 5 

“NONDESTRUCTIVE INSPECTION” (NDI). 

 Perform FLUORESCENT DYE PENETRANT structural inspection as an aid in disclosing crack 

indications or other failures not detectable by visual means. Carefully remove sealant and / or finishes as 

necessary in order to allow inspection of the structural elements. Moderate hand pressure applied 

between parts, in order to produce any relative movement allowed, may assist in detection of failure of 

parts or joining fasteners. Also observe any rub marks indicating relative movement of parts under load. 

 Perform EDDY CURRENT structural inspection as an aid in disclosing subsurface crack indications or 

other failures not detectable by dye penetrant means. Fastener holes must be properly reamed before 

completing eddy current inspections, otherwise false results might be obtained. 

Areas to be inspected are identified by Part Number and / or Name and are located per the applicable 

INSPECTION FIGURE(S).

NOTE:

ILLUSTRATED PARTS CATALOG MAY BE USED FOR ASSISTANCE IN LOCATING INSPECTION 

AREAS (REFERENCE ONLY). INSPECTIONS APPLY TO LEFT AND RIGHT HAND SIDES UNLESS 

OTHERWISE INDICATED. ONLY THE ODD NUMBER PARTS AND ASSEMBLIES ARE REFERED TO 

IN THE FOLLOWING TEXT. EVEN NUMBERS ARE EQUAL APPLICABLE OPPOSITE PARTS. 
SERVICE BULLETIN 241

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INSPECTION REQUIREMENTS:

1. PERSONNEL QUALIFICATION 

a. NDI Level II or Level III. 

b. Shall be qualified and certified in accordance with ASNT Personnel Qualifications SNT-TC-1A, 

ANSI / ASNT CP-189, NAS 410, or MIL-STD-410. 

 

2. MATERIALS AND EQUIPMENT 

a. Only materials listed or approved for listing per document QPL-AMS 2644 or QPL-25135 

(Qualified Products List) shall be used for penetrant inspections. Cleaner, Penetrant and Developer to be 

from the same product manufacturer. 

b. Solvent Removable Fluorescent Penetrant, per ASTM-E1417 or SAE-AMS 2644 specifications, latest 

revision. 

c. Solvent Remover (Class 1), per ASTM-E1417 or SAE-AMS 2644 specifications, latest revision. 

d. Nonaqueous Developer (Form D), per ASTM-E1417 or SAE-AMS 2644 specifications, latest revision. 

e. Black Lights used for viewing & inspection must meet ASTM-E1417 specifications, calibrated per ANSI / 

NCSL Z540-1 or ISO 10012-1. 

f. Inspection mirror. 

3. CLASSIFICATION 

 a. Per ASTM-E1417 or SAE-AMS 2644 specifications, latest revision. 

b. Type 1 (Fluorescent Dye), Method C (Solvent Removable), Sensitivity Level 3 (High). 

c. Twin Commander Process Specification 130.17 “Eddy Current Flaw Detection in Aluminum Alloys”, latest 

revision. 
SERVICE BULLETIN 241

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Part I - ACCESS, DISASSEMBLY & INSPECTIONS:

See the appropriate section of the airplane maintenance manual for procedures and instructions on removing and 

re-installing applicable items listed below. 

1. Disconnect batteries. 

2. De-fuel the airplane. 

3. Shore the airplane at the wing jack pad (Item ) and tail tie down stand (Item ) per FIGURE #2 and level 

per Maintenance Manual instructions. 

4. Complete shoring and leveling procedures as outlined per FIGURE #2 for (items &) to prevent movement 

of the fuselage and wing structure. 

5. Remove the cabin interior (seating, side panels and head liner) components from (F.S. 126.00) aft to the 

pressure bulkhead web assembly located at (F.S. 178.81). 

a. Take necessary measures required to protect electrical and air-conditioning equipment on aft pressure 

bulkhead. 

b. Protect and remove the left and right hand cabin picture window assemblies. 
SERVICE BULLETIN 241

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Part I - ACCESS, DISASSEMBLY & INSPECTIONS: (continued) 

6. Baggage compartment area (Center Wing Fuel Tanks): 

a. Remove the baggage compartment forward and upper interior closeout panels as necessary to gain 

access to the aft side of the aft pressure bulkhead assembly and center wing fuel tanks. 

b. Disconnect the center wing fuel tank fittings and sump. Unbolt the lower fuel tank removable floor 

structure. Remove the lower fuel tank cell. Optional to remove the aft and outboard lower fuel tank 

panels. 

c. Remove the lower wing skin access door to gain access to the center wing upper fuel tank. Disconnect 

and remove the upper fuel tank cell. 

d. To gain access to the aft side of the wing main spar cap, remove the upper fuel tank liner panels. This 

will also allow access to fasteners being replaced common to the lower wing drag channel located inboard 

of W.S. 24.07. 

e. Refer to K310384, Section G-G. Drill and remove the six (per side) existing rivets attaching the lower 

wing skins to the lower wing drag channel. 

CAUTION:

EXERCISE CAUTION WHEN REMOVING FASTENERS, DO NOT DRILL INTO THE MAIN SPAR 

LOWER CAP. 

f. Remove and cleanup any old residual sealant and tape from the aft side of the main spar cap web 

assembly from (W.L. -1.64 to W.L. -12.18) and from (L.B.L. 15.00 & R.B.L. 15.00 outboard). 

CAUTION:

AVOID THE USE OF TOOLS WHICH MAY CUT OR SCRATCH ALUMINUM SURFACES. 

7. Inboard wing area (directly outboard of W.S. 24.07): 

a. Remove the upper wing fuel tank access doors (forward and aft) of the main spar cap assembly. 

b. Disconnect the inboard wing fuel tank fittings and remove or push back the fuel tank bladders to gain 

adequate access to the outboard side of the W.S. 24.07 rib. 

c. Refer to K310384, Section G-G and Figure #3. Drill and remove the existing rivets attaching the lower 

wing to fuselage fillets fore and aft of F.S. 178. Caution: Do not remove existing rivets common to the 

W.S. 24.07 rib lower return flange (inboard flush row under fillet). 

NOTE:

SOME AIRCRAFT MAY HAVE PRIOR INSTALLED REPAIRS OVER THE EXISTING LOWER WING 

TO FUSELAGE FILLET ANGLES. PRIOR REPAIRS MUST BE EVALUATED FOR THE AFFECTS ON 

COMPLIANCE WITH THIS SERVICE BULLETIN. CONTACT TWIN COMMANDER AIRCRAFT IN THE 

EVENT PRIOR REPAIR WILL NOT BE COMPLETELY REMOVED BY THIS BULLETIN.

d. Remove the four screws / Huck bolts common to the lower wing to fuselage fillet and main spar lower cap 

outboard of W.S. 24.07. If the aircraft has complied with SB 164, these fasteners may have already been 

changed. The original production version was MS27039 screws. These four (per side) existing fasteners 

must be removed to allow for additional modification parts. 
SERVICE BULLETIN 241

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Part I - ACCESS, DISASSEMBLY & INSPECTIONS: (continued) 

e. Eddy Current inspect the existing fastener holes common to the main spar lower cap forward and aft 

flange per FIGURE #3. Prior to Eddy Current inspection, existing holes must be within limits indicated per 

Dwg No. K310384, General Note #8. Identify and record any damage found on the SB 241 

Compliance Card. Provide photographs of the damage.

f. Fluorescent Dye Penetrant inspect the 110151-33 fillet radius 4.0-inch fore / aft of F.S. 178.81 per 

FIGURE #3 for crack indications. Note: Stop drill extreme ends of cracks with #40 drill (0.098 dia.) and 

rout along the fore / aft length of crack (0.098 dia.) after completion of Part I, Item #11. Stop drill holes 

and routed areas must maintain a minimum of 2 X fastener diameter (edge distance) from the center of 

existing fastener hole locations. If measured crack lengths are within limits, it is acceptable to proceed 

with the modifications per Dwg No. K310384-503 instl. If crack lengths exceed limits indicated or edge 

distance is below minimums, part must be removed and replaced with a new part or an approved repair 

must be installed prior to return to service. Identify and record any damage found on the SB 241 

Compliance Card.

8. Aft fuselage compartment area (Picture Window): 

a. Refer to K310384, Section A-A. Drill and remove the cabin inner skin structural panels and reinforcement 

gussets above the cabin picture window from F.S. 126.00 to F.S. 171.36. 

CAUTION:

EXERCISE EXTREME CARE WHEN DRILLING / REMOVING EXISTING FASTENERS. DO NOT 

OVERSIZE OR DOUBLE DRILL EXISTING HOLES IN ATTACHING STRUCTURE. 

b. Refer to K310384, Section A-A. Drill and remove the cabin inner skin structural panels and reinforcement 

gussets aft of the cabin picture window from (F.S. 172.50 to F.S. 178.81) from (W.L. -8.00 to W.L. -35.25). 

NOTE: 

THE CABIN FLOOR IS AT W.L. -55.50.
SERVICE BULLETIN 241

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Part I - ACCESS, DISASSEMBLY & INSPECTIONS: (continued) 

NOTE:

IF ANY OF THE CABIN INNER SKIN STRUCTURAL PANELS HAVE BEEN MODIFIED WITH 

ADDITIONAL ACCESS HOLES OTHER THAN THE FACTORY RETURN FLANGED PARTS, THEY 

MUST BE REMOVED AND REPLACED WITH NEW PARTS OR AN APPROVED REPAIR MUST BE 

INSTALLED PRIOR TO RETURN TO SERVICE. 

9. Refer to K310384, Section A-A. Remove the 310704-1 channel by removing the fastener row common to the 

lower wing to fuselage fillet from F.S. 126.00 to F.S. 178.81. Remove the shear clips that attach the channel 

to the frames. 

NOTE:

IF THE EXISTING 310704-1 UPPER PICTURE WINDOW CHANNEL HAS BEEN PRIOR REMOVED 

AND REPLACED WITH THE IMPROVED 310704-3 CHANNEL, THEY MAY BE LEFT IN PLACE WITH 

THE OPTION TO REMOVE AND REINSTALL. 

a. Partial removal of the right side upper fuselage ice shield is required to access existing flush skin rivets 

attaching the upper picture window channel. 

b. After removal of the existing picture window channels from the aircraft, remove and cleanup any old 

residual sealant left in place that may interfere with the new channel replacement. 

c. Fluorescent Dye Penetrant inspect the removed channels outboard flange, radius and web – complete 

length - for damage. Cracks have been found along the outboard return flange (rivet hole to rivet hole) 

and along the parts lower web at areas common to the stub frame shear clip outboard attachment 

fasteners. Identify and record any damage found on the SB 241 Compliance Card. Provide 

photographs of the damage.

10. Refer to Figure 1. Remove the two horizontal pin and collar type fasteners attaching the 310412-23 shear 

clips. Note: During removal of these fasteners, inspect each fasteners pin / collar for working, tension or 

shear type damage. Identify and record any damage found on the SB 241 Compliance Card. Provide 

photographs of the damage.

11. Removal of the 310384-65/-125 channels and upper 310384-159 web. 

a. Refer to K310384-501. Remove remaining fasteners (including the two .250-inch diameter bolts common 

to the upper and lower wing main spar caps) attaching the 310384-65/-125 channels web. 

b. Refer to. K310384 Sect E-E. Remove fasteners from outboard fuselage skin below the wing to W.L. 

-28.00. Remove and retain the shear clip attaching the existing lower picture window channel. Note: The 

W.L. -28.00 clip will be reinstalled later. 

c. Refer to Figure 1. Remove and discard the 310736-45 shear clip attaching the upper picture window 

bulbed angle at W.L. -8.00 to the inboard flange leg of the 310384-65/-125 channels. 

d. Refer to K310384-501. Remove fasteners (including the two .250-inch diameter bolts common to the 

upper and lower wing main spar caps) attaching the 310384-193 channels from (W.L. -1.64 to W.L. 

-28.00). Remove all fasteners between the two vertical wing support channels. Remove fasteners 

common to the lower fuel tank support structure and field fasteners attaching the 310384-159 web to the 

aft pressure bulkhead from (W.L. -1.64 to W.L. -28.00). 

e. Refer to K310384-501. Determine the cut line (W.L -25.8 & L.B.L. 16.4) for the 310384-159 web. Insert 

stainless steel shim stock on the aft side of the 310384-159 web and aft attaching structure before cutting. 

Cut and remove the indicated section of 310384-159 web and remove. 
SERVICE BULLETIN 241

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Part I - ACCESS, DISASSEMBLY & INSPECTIONS: (continued) 

f. Refer to K310384-501. Fluorescent Dye Penetrant inspect the 310384-159 web outboard edge between 

(W.L. -10.0 to W.L. -12.18) for damage. Identify and record any damage found on the SB 241 

Compliance Card. Provide photographs of the damage.

g. Refer to K310384-501. Determine the approximate cut line (W.L -20.15 +/- .10) for the 310384-65/-125 

channels. This location may vary slightly depending on the original fasteners location. Maintain a 

minimum of .36-inch edge distance from the channel cut line to the center of existing fastener hole 

locations. If necessary, the cut may be slightly angled to maintain these minimums. Additional material 

has been left on the replacement 310364-3 channels upper and lower ends to allow for vertical 

adjustment while locating the new parts. 

h. Refer to K310384-501. After the cut locations have been marked, insert stainless steel shim stock on the 

outboard side (between the 310384-65/-125 channel and fuselage skin). Cut and remove the upper 

section of the -65/-125 channels. 

i. Fluorescent Dye Penetrant inspect the removed 310384-65/-125 channels outboard flange, radius and 

web 4.0-inch above and below W.L. -12.18 for damage. Identify and record any damage found on the 

SB 241 Compliance Card. Provide photographs of the damage.

12. Main spar lower cap forward flange radius and upper and lower main spar .250-inch diameter bolt holes 

inspection: 

a. Refer to Figure #4. Remove residual sealant from the local area (W.S. 24.07 / W.L. -12.18) to allow the 

radius of the spar forward flange to be cleaned and polished to a 32 RMS finish. 

b. Fluorescent Dye Penetrant inspect .50-inch radius along the cutout of the forward flange at W.S. 24.07 on 

the main spar lower cap. 
SERVICE BULLETIN 241

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Part I - ACCESS, DISASSEMBLY & INSPECTIONS: (continued) 

c. Refer to K310384 Section L-L. If a crack is detected in the main spar lower cap radius, contact Twin 

Commander Aircraft LLC. Aircraft is not to continue in service. If no cracks are found, check the main 

spar lower cap radius to be certain that machined transition area of the forward flange has a minimum 

radius of .50-inch and surface finish 32RMS or better. In addition, the lower main spar steel strap (.032-

inch thick) also follows this .50-inch radius trim common to the forward flange. Ensure the steel straps 

edge is flush with the spar radius trim. If the straps edge is not flush with the forward flange radius, trim 

flush with spar radius and provide surface finish 32 RMS or better at this location. 

d. If the inspection reveals any deviation (except cracking), proceed as follows. Provide surface finish 

32RMS or better to any rough areas, notches or machine marks in the radius area while maintaining a 

minimum radius of .50-inch and a surface finish of 32 RMS. 

CAUTION:

MAINTAIN 2D EDGE DISTANCE ON ALL FASTENERS. DO NOT CUT INTO THE VERTICAL LEG OF 

THE MAIN SPAR LOWER CAP. 

e. After the main spar lower cap radius has been inspected, restore sealant and finishes. Identify and 

record any damage found on the SB 241 Compliance Card. Provide photographs of the damage.

NOTE

PRIOR TO EDDY CURRENT INSPECTION OF EXISTING .250-INCH DIAMETER MAIN SPAR UPPER 

AND LOWER CAP HOLES, MUST REAMED WITHIN (.2659 /.2648 DIA). 

f. Fluorescent Dye Penetrant inspect .250-inch diameter holes in the upper and lower main spar caps for 

cracks per FIGURE #4. If a crack is detected, contact Twin Commander Aircraft LLC. Aircraft is not to 

continue in service. Identify and record any damage found on the SB 241 Compliance Card.

13. Corrosion preventative measures and sealants must be restored after inspections are completed. See part II, 

Item 12. NOTE. 

14. Fill out information on the SB 241 Compliance Card and send to: 

Twin Commander Aircraft LLC

Attn.: Service Department

1176 Telecom Drive

Creedmoor, NC. 27522

15. Part I, access, disassembly & inspections complete. 
SERVICE BULLETIN 241

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Part II - MODIFICATION & REASSEMBLY:

1. Baggage compartment area (Wing Drag Channel): 

a. Refer to K310384 Section G-G. Install six (per side) HL20PB-5 Hi-Lok fasteners. These Hi-Loks replace 

six removed solid fasteners per (Part I, Item #6, e). Fasteners attach the lower wing skin to the 310420-9 

wing drag brace channel. Remove and replace any additional working or damaged fasteners in the area 

with the same type and size removed. 

2. Inboard wing area (Wing to Fuselage Fillet): 

a. Refer to K310384-503. Position, drill and install the 310364-13 filler, -15 filler, -17 angle and -19 strap. 

Additional material has been left on these parts to allow trimming upon installation. The total fastener 

count per -503 instl to be maintained. Note: Any damage to the existing lower fuselage fillet radius to be 

stop drilled and routed out per Figure 3, before reinforcement parts are installed. 

b. Install clecos as required, to position parts. Only install fasteners along the outbd flange of the added fillet 

angle (-17) at this time, due to sequencing (see sect F-F). Refer to Dwg No. K310384, General Note #8 

for applicable fasteners attaching through the main spar lower cap forward and aft flanges. Refer to Dwg 

No. K310384, General Note #2 for application of sealant. 

c. Ensure the modification parts and sealant does not cover or plug the lower wing skin drain holes. 

d. Only install fasteners in the vertical flange of the added fillet angles located aft of F.S. 178.81. Do not 

install the existing fastener located in the F.S. 178.81 frame line / skin lap or any fastener forward other 

than with clecos at this time. These fasteners to be coordinated with the following item 7.e. 

e. Refer to Dwg No. K310384, General Note 6 for application of sealant. 

3. Fuselage to Wing Joint Area (Upper/Outer Frame and Pressure Web Mod): 

a. Refer to K310384-501. Position the 310364-11 web in place. It will be necessary to drill out and remove 

three to four fasteners below W.L. -28.00 attaching the existing 310384-65/-125 & -193 channels to the aft 

pressure bulkhead web to allow the -11 web to be positioned. Remove the existing bulbed tee angle 

installed at L.B.L. 11.7 (extends from the upper to lower main spar caps) if required, to install the 310364-

11 web. Reinstall bulbed tee with same type and size fasteners as removed or acceptable to substitute 

fasteners per Dwg No. K310384, General Note #10. Additional material has been left on the upper, lower 

and inboard ends of the -11 web to allow trimming as necessary for adjustment based on existing fastener 

locations. The total fastener count as shown on Dwg No. K310384-501 instl to be maintained. 

b. After the -11 web has been trimmed and placed into position, match drill existing fastener locations along 

the length of the 310384-193 channel and support with Clecos. Note: Additional added fasteners have 

been inter spaced between existing locations common to the 310384-193 channel between (W.L. -12.18 

to W.L. -27.6). This provides a double fastener row along the inboard splice edge of the -11 web. Double 

fastener row is also between (W.L. -25.8 to W.L. -27.6). 

NOTE: 

TO PREVENT A GAP BETWEEN PARTS AND FASTENER PRELOAD, INSTALL 170468-5 SHIMS 

(TRIM AS NECESSARY) OR FABRICATE TAPERED ALUMINUM SHIMS ON THE ENDS OF PART 

TRANSITIONS AS INDICATED PER DWG NO. K310384, GENERAL NOTE #4 
SERVICE BULLETIN 241

Page 14 of 20

Part II - MODIFICATION & REASSEMBLY: (continued) 

c. Refer to K310384-501. Position the 310364-3 channel on the forward side of the 310384-65 channel 

which was prior cut at approximately W.L. -20.15. The -3 channel has been machined down to nest into 

the lower remaining section of the 310365-65 channel approximately 5.6-inches to form a lap splice for 

the frame directly above W.L. -25.8. Additional material has been left on the upper and lower ends of the 

-3 channel to allow trimming as necessary for fastener adjustment. 

CAUTION: 

ONLY SLIGHT TO MODERATE HAND PRESSURE SHOULD BE EXERTED TO NEST THE LOWER 

END OF THE 310364-3 CHANNEL INTO THE UPPER TRIMMED END OF THE EXISTING 310384-65 

CHANNEL. DO NOT FORCE -3 CHANNEL INTO POSITION BY PRELOADING EXISTING -65 

CHANNEL. IF INTERFERENCE OCCURS, CONTACT TWIN COMMANDER AIRCRAFT LLC FOR 

DISPOSITION. 

d. Position the 310364-5 strap into the 310364-3 channel from (W.L. -1.64 to W.L. -23.95). The upper 

existing fastener hole location (HL64PB-8) to maintain.50-inch minimum edge distance on the -5 strap 

upper machined end. The lower machined end to be located at an existing #5 rivet hole. Maintain a 

minimum edge distance of .36-inch. Additional material has been left on the upper and lower ends of the 

-5 strap to allow trimming as necessary for adjustment based on existing fastener locations. 

CAUTION: 

BEFORE INSTALLING THE 310364-3 CHANNEL VERIFY THE CLEARANCE BETWEEN THE MAIN 

SPAR LOWER CAP FORWARD FLANGE .50-INCH RADIUS AND THE OUTBOARD FLANGE RADIUS 

OF THE REPLACEMENT 310364-3 CHANNEL (SEE FIGURE 4). INSERT FEELER GAGES INTO THE 

JOINT TO ENSURE A MINIMUM CLEARANCE OF .032-INCH. (REFER TO DWG NO. K310384, 

SHEET 2 OF 4, SECTION L-L). OPTIONAL TO USE A RAPID CURE HARDENING PUTTY THAT MAY 

BE REMOVED AND MEASURED TO DETERMINE CLEARANCE. CHECK FOR PRELOAD IN ALL 

MATING PARTS. DO NOT FORCE PARTS, USE FLAT OR TAPERED ALUMINUM SHIMS PER 

K310384 NOTE 4. 

e. Refer to K310384-501. Match drill -3 channel and -5 strap to existing fastener holes where applicable. 

4. Upper picture window channel area: 

a. Refer to K310384, Section B-B. Position the 310704-3 channel replacement above the picture window 

from (F.S. 126.00 to F.S. 178.81). Note: If necessary, trim aft end of 310704-3 channel to clear forward 

flange legs of 310364-3 channel, maintaining .050-inch clearance. 

b. Match drill the 310704-3 channel to the existing shear clip attachment fasteners between (F.S. 126.00 

through F.S. 172.50). Match drill along the outboard flange leg attaching to the outer fuselage side skin 

and Cleco into position. Refer to Dwg No. K310384, General Note #15 for additional installation 

instructions and limitations regarding the 310704-3 channel. 
SERVICE BULLETIN 241

Page 15 of 20

Part II - MODIFICATION & REASSEMBLY: (continued) 

5. Machined tee clip instl (Forward side of F.S. 178.81 & W.L. -14.00) area: 

a. Refer to K310384-Section A-A, B-B,& C-C. Position the 310364-7 tee with the forward horizontal flange 

leg against the lower side of the 310704-3 channel web to determine the trim angle for the aft vertical 

flange leg. (Optional to use a mechanical protractor / angle finder or other device). Alignment variances 

related to the aft end of the 310704-3 channel will require the 310364-7 tee to be trimmed on installation. 

Additional material has been left on the aft vertical flange leg (inbd / outbd) of the -7 tee to allow rotation 

on the parts axis +/- 6 degrees. This will allow the forward flange leg to align with the 310704-3 channel 

aft end. Refer to Dwg No. K310384, General Note #19 and Figure #1 located on Sheet 2 of 4 for 

minimum trim dimensions. Restore part primer finish after trimming and de-burring. 

b. After the -7 tee has been trimmed and corrosion protection restored (Refer to Dwg No. K310384, General 

Note #19), locate the tee into the frame and mark existing hole locations on the tee from the baggage 

compartment. Remove tee and determine if marked hole locations are acceptable by maintaining a 

minimum of 2D edge distance. If hole locations are not acceptable, contact Twin Commander. If hole 

locations are acceptable, match drill all -7 tee clip holes (8) and Cleco into place. Use of shims between 

the tee horizontal flange and upper picture window channel is acceptable to prevent fastener preload on 

assembly. 

c. If there are alignment issues, do not preload parts. Refer to Dwg No. K310384, General Note #4 for 

additional instructions pertaining to shimming of parts. 

6. Machined strap instl (Aft side of F.S. 178.81 & W.L. -14.00) area: 

a. Refer to K310384-Section A-A, B-B & C-C. From the baggage compartment, locate the 310364-9 Strap 

per section A-A. Remove the -7 Tee and mark the 4 attaching fastener locations on the -9 strap from the 

cabin side. It is acceptable to trim the lower edge of 310420-13 clip to allow -9 strap to seat and maintain 

2D edge distance on the upper fastener. Remove the strap and determine if drilled hole locations are 

acceptable. If hole locations are not acceptable, contact Twin Commander. DO NOT INSTALL -9 

STRAP AND -7 TEE FASTENERS UNTIL ITEM 7.b. IS COMPLIED WITH. 

NOTE: 

SOME AIRCRAFT MAY BE CONFIGURED WITH AN EXISTING SHIM OF VARYING THICKNESSES 

INSTALLED BETWEEN THE 310420-13 CLIP AND THE AFT PRESSURE BULKHEAD WEB. THIS 

SHIM WAS INSTALLED BY THE FACTORY AND MUST BE REPLACED WITH A LARGER SHIM (TO 

ACCOMMODATE THE 310364-9 STRAP ADDITIONAL LENGTH) MADE FROM THE SAME 

THICKNESS AS REMOVED. REFER TO DWG NO. K310384, GENERAL NOTE #4 FOR ADDITIONAL 

INSTRUCTIONS PERTAINING TO SHIMMING OF PARTS. 
SERVICE BULLETIN 241

Page 16 of 20

Part II - MODIFICATION & REASSEMBLY: (continued) 

7. Remove all Cleco attached parts per Part II, Items #3 through #6. 

a. Refer to K310384-Section D-D. Reinstall 310364-11 web, -3 channel and -5 strap in the same sequence 

as they were initially placed and located. Mark all fastener locations prior to drilling to verify they can be 

installed. If fastener heads or butts interfere move fastener to clear. Note: If required, the outboard 

forward edge of the 310364-5 strap may be chamfered .063 x 45 degrees to provide clearance for solid 

rivet butts along the outboard flange. 

b. DO NOT REINSTALL 310364-7 TEE UNTIL: 

1) Refer to K310384-501, -503, & Section E-E. 310364-3 channel outboard flange rivets in the area of 

the 310364-7 tee require special installation instructions. Three existing #5 rivets reinstalled in the 

outboard skin channel flange (Highlighted in yellow, coded as “A” – Sect E-E) must have the rivet butt 

flushed to clear the 310364-5 strap and 310364-7 tee. Back countersink the inboard side of the hole 

100 degree by .037-inch deep. Install fasteners with the manufactured heads on the outboard side 

and buck the tail into the countersink. Acceptable to grind rivet butt flush with surrounding material. 

Restore corrosion protection to shaved rivets (Refer to Dwg No. K310384, General Note #19) 

2) Part II, fitting process complete. 

CAUTION: 

THE SUBSTITUTION OF BLIND RIVETS OTHER THAN THOSE INDICATED ON TWIN COMMANDER 

DWG NO. K310384 IN THE GENERAL NOTES OR ON THE FIELD OF DRAWING IS NOT PERMITTED 

WITHOUT AUTHORIZATION FROM THE AIRFRAME MANUFACTURE OR APPROVED BY A 

REPRESENTATIVE OF THE FAA. 

c. Refer to K310384-501, section E-E. Cleco the 310364-5 strap, 310364-7 tee and 310364-9 strap in 

place. 

d. Refer to K310384-501. Install fasteners attaching the 310364-5 strap, 310364-7 tee and 310364-9 strap. 

Note: Four fasteners attaching the -7 tee, require a special hole size per Dwg No. K310384, General 

Note #5. Do not use reamer sizes for these fasteners as indicated on Dwg No. K310384, Rivet Code 

Block for these four fasteners. Seal all parts per K310384, General Note #2. 

e. Refer to K310384 Section A-A. Install or reinstall the 310704-3 channel over the picture window. 

Reinstall all fasteners at stub frame shear clips and along the outboard flange / skin attachment with the 

same type and size fastener removed. Optional, to substitute hardware per Dwg No. K310384, General 

Note #10, #15 and #20. Part II, Item #2, d. may be completed at this time per Dwg No. K310384-503. 

Seal all parts per K310384, General Note #2. 

8. Before the cabin inner frame panel liners are reinstalled. 

a. For detailed procedures regarding fuselage sealing, Refer to Twin Commander Aircraft LLC, Service 

Letter No. 382 “SEALING CABIN LEAKS IN AIRCRAFT PRESSURIZED TO THE FLOOR”, latest 

revision. 

b. All pressure boundary reworked areas that will be inaccessible once the panels are reinstalled should be 

checked for adequate sealant coverage. Particular attention to the area outboard of the added 310364-3 

channel between (W.L. -1.64 and W.L. -12.18). 

c. All applicable replaced and added fastener heads and or butts to be sealed per Service letter No 382. 

d. If the fiberglass cloth / sealant was damaged covering the engine throttle control cables aft of F.S. 144.00 

during the removal of the 310704-1 channel, refer to Twin Commander Aircraft LLC, Service Letter No. 

382 “SEALING CABIN LEAKS IN AIRCRAFT PRESSURIZED TO THE FLOOR”, latest revision.” for 

application procedures on restoring the fuselage seal. 
SERVICE BULLETIN 241

Page 17 of 20

Part II - MODIFICATION & REASSEMBLY: (continued) 

9. Cabin inner frame panel area (Picture Window support panels): 

a. Refer to K310384 Section A-A. Position the existing 310736-85 and -143 inner skin panel in place. 

Match drill existing fastener hole positions from the inner skin panels to the 310704-3 channel. Install 

Cleco fasteners in the panels to hold in place. See CAUTION item 10.a. 

b. Refer to K310384-505. Position the 310364-21 doubler on the upper aft corner of the inner frame skin 

panels. Additional material has been left on this part to allow trimming as necessary for adjustment due to 

existing fastener locations. Note: The 310364-21 doubler design replaces the factory installed 310736-

13 gusset and 310736-81 doubler. These parts will not be reused and may be discarded. Refer to Dwg. 

No. K310384, General Note #13. 

c. Refer to K310384-505 & Section A-A. After the outer perimeter of the 310364-21 has been located, 

match drill existing fastener holes. Install adequate Cleco fasteners to hold in place. Layout the trim lines 

for the added access hole installed fore / aft between (F.S. 172.50 and F.S. 178.81) and vertically 

between the 310704-3 channel and existing 310736-91 angle. The upper and lower cut out edges of the 

access hole to be flushed with the channel and angle parts edge. For locating the fore / aft cut out 

location of the access hole, Refer to K310384-505 and General Note #12. 

d. Make the access hole cutout in the existing 310736-143 panel and added 310364-21 doubler. 

e. Refer to K310384-505. Four (per side) of the existing fastener holes in the 310736-91 angle will be 

converted into removable bolts and nutplates. 

f. Refer to K310384-505. Position the 310364-25 door over the 310364-21 doubler. The 310364-25 door 

has four pilot hole locations used to locate the additional bolts and nutplates. 

g. Match drill 310364-25 door to the existing 12 fastener hole locations (.1895 / .1915-in. dia. holes) in the 

310364-21 doubler. Do not install 310364-25 door at this time. 

h. Refer to K310384 & Section A-A. Install a new shear clip to replace the prior removed 310736-45. This 

clip attaches the existing aft end of the 310736-91 angle to the inboard flange leg of the added 310364-3 

channel. 
SERVICE BULLETIN 241

Page 18 of 20

Part II - MODIFICATION & REASSEMBLY: (continued) 

10. Cabin inner panel to aft pressure bulkhead web attachment area: 

a. Refer to K310384-505 & Section H-H. Position the 310364-23 angle as shown along the inboard side of 

the added 310364-3 channel and added 310364-21 doubler. Additional material has been left on this part 

to allow top and bottom trimming as necessary for adjustment based on existing fastener locations. The 

total fastener count as shown on Dwg No. K310384-505 instl must be maintained. 

CAUTION:

DO NOT MATCH DRILL THE EXISTING FOUR FASTENER HOLE LOCATIONS (HIGHLIGHTED IN 

GREEN, CODED AS “B”) COMMON TO -23 ANGLE AND 310364-3 CHANNEL. THESE HOLES 

ONLY ATTACH THE 310364-21 DOUBLER TO THE 310364-23 ANGLE. DAMAGE TO THE PRIOR 

INSTALLED 310364-7/-8 TEE WILL RESULT IF THESE HOLES ARE MATCH DRILL TO THE 310364-

3 CHANNEL. THE FOUR EXISTING HOLES IN THE 310736-143 PANEL MUST BE DOUBLE FLUSH 

INSTALLED WITH AD RIVETS PER DWG. NO. K310384, GENERAL NOTE #14. 

b. Refer to K310384, Note 14. Match drill existing fastener hole locations from the 310736-143 inner skin 

panels to the outboard flange leg of the 310364-23 angle, except the four per Caution Note. Using a hole 

finder, locate and drill the four additional fasteners holes (Highlighted in green, coded as “B”) on the 

outboard flange of the -23 angle. Attach the -23 angle and -21 doubler together with four NAS1097E5 or 

KE5 rivets with the manufactured head countersunk into the outboard side of the -21 doubler. 

c. Refer to K310384, Note 16 and 17. Locate the -21 doubler with the -23 angle attached, to the 310736-

143 panel with clecos. Match drill the existing fastener, common to the main spar lower cap vertical 

flange. If this fastener cannot be installed, see notes 16 & 17 for options. 

d. Refer to K310384, Section H-H. Locate, drill and install the remaining additional fasteners attaching the 

aft flange of the 310364-23 angle to the 310364-11 web maintaining a minimum of .23-inch edge 

distance. Seal all parts per K310384, General Note #2. 

e. Refer to K310384-505. Install fasteners attaching the outboard flange leg of the 310364-23 angle, 

310364-21 doubler and 310736-143 panel. Note: These fasteners are not required to be installed wet or 

sealed over with sealant. 

f. Refer to K310384, Note 15. Reinstall remaining inner skin panels between (F.S. 126.00 and F.S. 171.36) 

with the same type and size fastener removed. Optional to substitute fasteners per, General Note #15.

Note: These fasteners are not required to be installed wet or sealed over with sealant. 

11. Cabin inner frame panel access door: 

a. Refer to K310384-505. Locate and install the 310364-25 door with the hardware indicated. Torque 

AN173-5A bolts to 25-35 inch-lbs. 
SERVICE BULLETIN 241

Page 19 of 20

Part II - MODIFICATION & REASSEMBLY: (continued) 

12. Corrosion preventative measures and sealants must be restored after inspections are completed. 

13. Reinstall the left and right hand cabin picture window assemblies. 

14. All replacement fasteners installed in the center wing upper and lower fuel tank compartments to have a 

minimum of two layers of tape per parts kit item 8 to cover fastener heads / butts that may contact the fuel 

tank cell. It is not necessary to cover fasteners with tape that are concealed by the tank panel liners. 

Reinstall all tank panel liners with the same type and size fasteners that were removed. Seal all tank panel 

liner fasteners that penetrate through the aft pressure bulkhead web at F.S. 178.81 pressure boundary. 

16. Reinstall the center wing fuel tank support foam (installed on inboard / outboard sides of access hole / door. 

Replace if necessary. Reinstall fuel tank cell and access door. 

17. Reinstall the center wing lower fuel tank support structure with the same type and size fasteners as removed. 

Reinstall fuel tank cell and reconnect all tank and pump fittings. 

18. Reinstall the left and right inboard wing fuel tank cells and ensure none of the replaced fasteners contact the 

fuel tank cell and reconnect all tank fittings. Reinstall fuel sump. 

19. Complete fuselage leak check of the pressurized cabin. 

20. Complete leak check of the reinstalled fuel system. 

21. CABIN SEALING 

For detailed procedures regarding fuselage sealing, Refer to Twin Commander Aircraft LLC, Service Letter 

No. 382 “SEALING CABIN LEAKS IN AIRCRAFT PRESSURIZED TO THE FLOOR”, latest revision. 

22. Part II, modification and reassembly complete. 

ELECTRICAL LOAD:

No change 

WEIGHT AND BALANCE:

No significant change 

SPARES AFFECTED:

None 
SERVICE BULLETIN 241

Page 20 of 20

RECORD COMPLIANCE:

Make an entry in the Aircraft Maintenance Records as follows: Service Bulletin No. 241, dated September 26, 

2012, entitled “FUSELAGE ATTACHMENT TO WING MAIN SPAR - INSPECTION & REINFORCEMENT”, 

complied with as follows: 

SB 241, Part I & II have been accomplished on aircraft model ________, serial number ________, with a current 

total airframe time of ___________ hours. No recurring inspections are required, SB 241 is terminating action. 

Fill out information on the Compliance Card and mail postage paid form to: 

TWIN COMMANDER AIRCRAFT, LLC.

Attn.: SERVICE DEPARTMENT

1176 TELECOM DRIVE

CREEDMOOR, NC. 27522 

 or FAX to: (919)-682-3786 
Page 1 of 4

SB 241 COMPLIANCE RECORD 

(Please fax to Twin Commander at # 919-682-3786 

or mail this postage paid form to address on reverse.) 

SERVICE BULLETIN NO. 241 

FUSELAGE ATTACHMENT TO WING MAIN SPAR – 

INSPECTION & REINFORCEMENT

 MODEL _________ S/N ____________ REG. NO. ___________ TOTAL TIME ___________(HOURS) 

 OWNER NAME ____________________________________________________________________ 

 ADDRESS ________________________________________________________________________ 

 TELEPHONE NO. ( ) FAX NO. ( ) 

DAMAGE REPORT DURING COMPLIANCE WITH SB 241 -------------------------------------------------------------------------------------------------------------------------------------------- 

 Part I: (Has the aircraft undergone prior compliance with Twin Commander Custom Kit No. 

144 for the removal and replacement of the main spar lower cap) 

 YES  / NO  

 If Yes, date and total time when accomplished _____________________________ 

-------------------------------------------------------------------------------------------------------------------------------------------- 

 Part I, Item #7, e: (Eddy Current inspection of the four LH and four RH holes common to the main spar 

lower cap fwd / aft flange outbd of W.S. 24.07) 

 Damage found: YES  / NO  

-------------------------------------------------------------------------------------------------------------------------------------------- 

 Part I, Item #7, f: (Fluorescent Dye Penetrant inspect the 110151-33/-34 fillet radius 4.0-inch fore / aft 

of F.S. 178.81) 

 Damage found: YES  / NO  

 Within limits: YES  / NO  -------------------------------------------------------------------------------------------------------------------------------------------- 

 Part I, Item #9, c: (Fluorescent Dye Penetrant inspect the 310704-1/-2 channel outbd flange and lower 

web from F.S. 126.00 to F.S. 178.81) 

 Damage found: YES  / NO  

 Prior replaced: YES  / NO (310704-3 LH / -4 RH) 

-------------------------------------------------------------------------------------------------------------------------------------------- 

 Part I, Item #10: (Inspection of the two LH and two RH pin and collar type fasteners attaching the 

310412-23/-24 shear clips for working of sheared conditions at F.S. 178.81 & 

W.L. -14.00) 

 Damage found: YES  / NO  

 What type of hardware was installed: 

-------------------------------------------------------------------------------------------------------------------------------------------- 

 cont. 
Page 2 of 4

DAMAGE REPORT DURING COMPLIANCE WITH SB 241 (cont.)

-------------------------------------------------------------------------------------------------------------------------------------------- 

 Part I, Item #11, f: (Fluorescent Dye Penetrant inspect the 310384-159 web outbd edge at the main 

spar cap relief trim from W.L. -11.0 to W.L. -12.18) 

 Damage found: YES  / NO  

-------------------------------------------------------------------------------------------------------------------------------------------- 

 Part I, Item #11, i: (Fluorescent Dye Penetrant inspect the 310384-65/-125 channels outbd flange, 

radius and web 4.0-inch above / below W.L. -12.18) 

 Damage found: YES  / NO  

-------------------------------------------------------------------------------------------------------------------------------------------- 

 Part I, Item #12, b: (Fluorescent Dye Penetrant inspect the .50-inch radius along the cutout of the 

forward flange at W.S. 24.07 on the main spar lower cap) 

 Damage found: YES  / NO  

 Evidence of part contact between the .50-inch radius or lower steel strap and the existing 

 310384-65/-125 channels outbd flange radius: 

 YES  / NO  

-------------------------------------------------------------------------------------------------------------------------------------------- 

 Part I, Item #12, f: (Eddy Current inspection of the four .250-inch diameter LH and four RH holes 

common to the main spar upper and lower caps vertical flange leg attaching the 

310384-65/-125 and 310384-193 channels) 

 Damage found: YES  / NO  

-------------------------------------------------------------------------------------------------------------------------------------------- 

 DATE ________ 

 WORK PERFORMED BY (PRINTED) 

 (SIGNATURE) 

 COMPANY ________________________________________________________________________ 

 ADDRESS ________________________________________________________________________ 

 ________________________________________________________________________ 

 TELEPHONE NO. ( ) FAX NO. ( ) 

 EMAIL ___________________________ 

 COMMENTS: ______________________________________________________________________ 

 __________________________________________________________________________________ 

 __________________________________________________________________________________ 

 __________________________________________________________________________________ 

 __________________________________________________________________________________ 
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