ALERT SERVICE BULLETIN
427-15-38
4 September 2015
Revision A, 14 November 2016
MODEL AFFECTED:
427
SUBJECT:
VERTICAL FIN 427-035-840-105 AND 427-035-840109, INSPECTION OF.
HELICOPTERS AFFECTED:
Serial numbers 56001 through 56084, 58001 and
58002.
COMPLIANCE:
PART I - Within the next 10 flight hours or 7 days,
whichever occurs first, after the date of issuance as
indicated on this bulletin revision A.
PART II - For affected vertical fins that have an
unknown total accumulated flight time or vertical fins
that have accumulated 1500 flight hours or more,
within the next 25 flight hours after accomplishment
of PART I and every 100 flight hours thereafter. This
recurring 100 hour inspection is not required until the
subject vertical fins have accumulated 1500 flight
hours.
DESCRIPTION:
Bell Helicopter Textron has received reports of vertical fin cracking. The cracks were
very similar and were located on the inboard skin at the upper aft tailboom attachment.
The initial release of this bulletin mandated a 300 hour recurring inspection of the
subject vertical fins. This inspection was also incorporated in Chapter 4 of the
maintenance manual.
Following further review and analysis, revision A of this bulletin is being released to
decrease the recurring inspection interval from 300 flight hours to 100 flight hours.
This recurring 100 hour inspection is now required only when subject vertical fins have
accumulated 1500 flight hours or more or for subject vertical fins having an unknown
total flight time. The maintenance manual Chapter 4 will be revised to reflect this
change.
ASB 427-15-38A
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At time of manufacturing, there was no requirement to serialize the vertical fins.
Therefore, some may not have a serial number. For tracking purposes, this bulletin
mandates a serial number to be assigned to vertical fins that do not have a serial
number. Note also that vertical fins that will be found with a crack will require
replacement before the next flight with no repair possibility.
Applicability of this bulletin to any spare part shall be determined prior to its installation
on an affected helicopter.
APPROVAL:
The engineering design aspects of this bulletin are Transport Canada Civil Aviation
(TCCA) approved.
CONTACT INFO:
For any questions regarding this bulletin, please contact:
Bell Helicopter Product Support Engineering - Intermediate Helicopters
Tel: 450-437-2077 / 1-800-463-3036 / [email protected]
MANPOWER:
PART I - Approximately 0.25 man-hours are required to complete PART I of this
bulletin.
PART II - Approximately 2 man-hours are required to complete PART II of this
bulletin. This estimate is based on hands-on time and may vary with personnel and
facilities available.
WARRANTY:
There is no warranty credit applicable for parts or labor associated with this bulletin.
MATERIAL:
Required Material:
None required.
ASB 427-15-38A
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Consumable Material:
The following material is required to accomplish this bulletin, but may not require
ordering, depending on the operator’s consumable material stock levels. This material
may be obtained through your Bell Helicopter Textron Supply Center.
Part Number
Nomenclature
Qty
Reference *
2010-05901-00
Corrosion Preventive
Compound
Cleaning Compound
A/R
C-586
A/R
C-318
2100-00006-00
* C-XXX numbers refer to the consumables list in the BHT-ALL-SPM, Standard Practices Manual
SPECIAL TOOLS:
None required.
WEIGHT AND BALANCE:
Not affected.
ELECTRICAL LOAD DATA:
Not affected.
REFERENCES:
BHT-427-MM, Maintenance Manual, Chapter 53
BHT-ALL-SPM, Standard Practices Manual, Chapter 8
PUBLICATIONS AFFECTED:
BHT-427-MM, Maintenance Manual, Chapter 4
ACCOMPLISHMENT INSTRUCTIONS:
PART I - Verification of affected vertical fin total flight hours.
1. Verify the helicopter’s technical records to determine the total accumulated flight
hours of the vertical fin.
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-NOTEVertical fins that have been inspected in accordance with the
initial release of this bulletin within 100 flight hours before the
release of this revision A, can be inspected within the next
100 flight hours after the last inspection has been
accomplished. In those cases, the vertical fin does not
require inspection within the next 25 flight hours as indicated
in the Compliance section. For example, if the vertical fin
was inspected 30 hours before the release of the revision A,
the next inspection can be accomplished 70 hours after the
release of the bulletin revision A.
a. If the vertical fin has accumulated 1500 flight hours or more in service or if the
vertical fin has an unknown total accumulated flight time, PART II of this bulletin
will require accomplishment as indicated in the Compliance section of this
bulletin revision.
b. If the vertical fin has less than 1500 flight hours in service, PART II of this
bulletin revision does not require accomplishment at this time.
-NOTEIf the vertical fin had a serial number assigned in
manufacturing, the data tag can be found in the middle
inboard section of the vertical fin in the attachment holes
area.
2. If the vertical fin has no data tag with a serial number, use the information
contained in the BHT-ALL-SPM, Chapter 8 to assign a serial number to the vertical
fin. For tracking purposes, a component Historical Service Record (HSR) should
also be created for affected vertical fins.
3. Make an entry in the helicopter logbook and historical service records indicating
findings and compliance with PART I of this Alert Service Bulletin.
PART II - Vertical fin inspection.
1. Prepare the helicopter for maintenance.
2. Remove the vertical fin (BHT-427-MM, Chapter 53).
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3. Prepare a soap solution (C-318) per the manufacturer’s recommendations. Clean
the vertical fin attachment area with the soap solution to remove all traces of dirt,
stains, exhaust residue, and oil. Rinse the area with water and let dry.
-NOTEIt is not necessary to remove the paint for the inspection
unless a crack is suspected.
4. Using a 10X magnifying glass and a bright light source, inspect the inboard skin of
the vertical fin around the four tailboom attachment points (Figure 1). Pay particular
attention to the upper aft attachment point.
a. If no crack or other defect is detected, go to step 5.
b. If a crack is detected, replace the vertical fin prior to next flight.
c. If any defect other than a crack is found, refer to BHT-427-MM, Chapter 53 for
inspection and repair.
5. Reinstall the vertical fin (BHT-427-MM, Chapter 53).
6. Make an entry in the helicopter logbook and historical service records indicating
findings and compliance with PART II of this Alert Service Bulletin.
ASB 427-15-38A
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Figure 1 - Inspection of Vertical Fin
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