Service difficulty report · Shaft · Bolkms BK117C2

Difficulty date
February 26, 2024
Submitted
February 26, 2024
Operation
General aviation
Filed by
QR9R369D
M1 Support Services
Make and model
Bolkms BK117C2
Aircraft serial
11721899447
Aircraft time
3,216 hours
Part
Shaft
Part number
10531803
Condition
Failed Insp
Location
Tail Rotor
Stage of operation
IN
How discovered
V
Nature of condition
O
Precautionary procedure
K

As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.

What was found

M1 HAS DISCOVERED A DESIGN/ENGINEERING FLAW BETWEEN THE AMM 65-11-00, 4-9 FIGURE 1/1 SHEET 3/3 AND THE CURRENT MANUFACTURING OF THE TAIL ROTOR OUTPUT SHAFT WHICH IS QUITE POSSIBLY THE ROOT CAUSE OF DAMAGE TO THIS COMPONENT. M1 HAS REPEATEDLY DISCOVERED DAMAGE TO THE SPLINES ON LAKOTA TAIL ROTOR OUTPUT SHAFTS (6 SINCE 16 JANUARY 2023). THIS HAS BEEN AN ON-GOING ISSUE SINCE FORT NOVOSEL RECEIVED THESE AIRCRAFT. AFTER INSPECTING THE TAIL ROTOR SHAFTS, QUALITY SUPERVISION DOES NOT SUSPECT THIS IS A MAINTENANCE OR A TRAINING PROBLEM. THIS DAMAGE IS MORE LIKELY ATTRIBUTED TO THE DESIGN OF THE SPLINES OR A POTENTIAL DESIGN FLAW. QC MONITORS THIS PROCESS WITH A TECHNICAL INSPECTOR AND MECHANICS ARE FOLLOWING THE DOCTRINE. QC HAS INSPECTED THE TOOLING AND DOES NOT SEE A PROBLEM WITH THE INSTALLATION OR REMOVAL TOOLS NOR THE DOCUMENTED PROCESS OF THE REMOVAL OR INSTALLATION PROCEDURE.