1. IMP AEROSPACE
Sea King Pylon Repair and Overhaul by Anick Chiasson Intermediate Aero/Mechanical Engineer Rotary Wing Engineering IMP AEROSPACE
IMP Aerospace, P.O. Box 970, Enfield, Nova Scotia, Canada B2T 1L5
Tel • Fax • .
Website.

2. Presentation Outline Introduction Overview of the Pylon
Areas of Interest on the Pylon
Engineering Process
Area 1: Tail Gearbox (TGB) Support Fitting
Area 2: Pylon Fold Fitting
Area 3: Oversized Rivets on left side of a Pylon
Area 4: Hinge fittings
Area 5: Oversized Fasteners at Hinge Fittings
Questions

3. Introduction of IMP Group Ltd.
Number of professionals
IMP Group Ltd.
IMP AEROSPACE & DEFENCE
IMP AEROSPACE Engineering Branch
Aeronautical Support Engineering
Rotary Wing Engineering
Fixed Wing Engineering
Specialty Engineering
= 22
= 26
= 12
= 32
Integrated Logistics Support (ILS)
Technical Publications
= 29
= 30

4. Overview of the Pylon
Pylon
The Pylon is the tail end of the aircraft.

5. Overview of the Pylon
The Pylon holds the Tail Rotor and the Stablilizer.
The Intermediate Gearbox (IGB) and the Tail Gearbox (TGB) are installed on the Pylon.
The Pylon is under intense load (torsion and bending).
The Pylon is a critical primary component of the Sea King.

6. Areas of Interest on the Pylon
Area 1: TGB Support Fitting
Area 4: Hinge Fittings
Area 2: Pylon Fold Fitting
Area 5: Oversized Fasteners at Hinge Fittings
Area 3: Row of oversized Rivets along LH side

7. Engineering Process
Sea King part or component is inducted in our facility.
The damage is assessed.
Production department requests Engineering services for a serviceability assessment.
Engineering team calculates safe limits for rework/repair.
Engineering team prepares a detailed repair scheme document.

8. Area 1 : TGB Support Fitting
Mounting Pads and Bolt Holes
Barrel Nut Holes
Damage found inside barrel nut bore holes and bolt holes
Damage found on Tail Gearbox (TGB) mounting pads

9. Area 2: Pylon Fold Fitting
The power fold system was added to the Canadian version of the Sea King.
Pylon Fold Fitting

10. Area 3: Oversized Rivets on left side of a Pylon
FWD
Rivet #1 UP
Row of oversized Rivets (Quantity 55) was discovered at overhaul. The rivets found were 1/4” and the OEM design was 3/16”.

11. Area 4: Hinge Fittings Upper Hinge Fitting (Top View)
Lugs
Upper Hinge Fitting
(Top View)
The lugs are two of the attachment points to the aircraft fuselage.
The four mounting pads are to install the Intermediate Gear Box.
IGB Mounting Pads

12. Area 5: Oversized Fasteners at Hinge Fittings
Upper Hinge Fitting
Hi-Lok fasteners qty 11 on either side at upper hinge fitting UP
FWD
Hi-Lok fasteners qty 8 on either side at lower hinge fitting

13. Area 5: Oversized Fasteners at Hinge Fittings
Initial Problems:
11 pylons with oversized fasteners at installation of Upper and Lower Hinge Fittings.
No approved documentations were found to substantiate the oversized fasteners.
Up to 0.292” from their original design size of 0.188”.
Biggest problem was the lack of acceptable edge distance (ED) on the different structure parts.

14. Area 5: Oversized Fasteners at Hinge Fittings
Assessment:
Option 1
Option 2
Repairing the pylon by replacing the structure affected; and revert to 3/16” fasteners:
400 man-hours per pylon
Lead time to get parts
Material cost
Manufacturing hours to manufacture parts needed
Analyzing the damage for serviceability:
The margins of safety of the Fittings were high
The skin, cap angles and doubler had to be analyzed
The analyses would render at least 8 pylons serviceable

15. Area 5: Oversized Fasteners at Hinge Fittings
Example of the multiple layers within the Pylon.
Plugging the oversized holes was required for this repair.

16. Area 5: Oversized Fasteners at Hinge Fittings
Results:
Engineering was able to analyze the structure with the oversized fasteners.
Those completed and approved analyses rendered 6 pylons serviceable.
More pylons will be deemed serviceable using the completed analyses.
Fatigue limits in terms of life span for each pylon were achieved.

17. Area 5: Oversized Fasteners at Hinge Fittings
Edge Distance (ED) less than 2D
Splice cut line
Example of spliced skin (above)
Example of less than 2D edge distance (left)

18. Questions
Thank you for the opportunity to highlight IMP’s Pylon R&O capabilities!
Please come see a Pylon at our booth to discuss any further questions that you may have!