A single mis-drilled fastener hole could have grounded a Beechcraft B200 for a long delay. Every hour counts when an aircraft is grounded. Instead, PartWorks supported a repair that got the aircraft back in service quickly with no engineering delays, and no follow-up inspections required.
| Aircraft | Beechcraft B200 |
|---|---|
| Problem | Mis-drilled fastener hole in left-hand forward spar cap |
| Structure | 0.250" 2014-T6511 extrusion + 2024-T351 Alclad plate |
| Solution | PartWorks dual bushing system (15-5PH CRES inner + 2024-T351 outer) |
| Result | Aircraft returned to service, standard fastener used, no engineering disposition required, no fatigue life impact |
| Push-out strength | 500+ lbs |
The Problem: A Damaged Hole in a Critical Part of the Aircraft
A technician discovered a structural discrepancy during the maintenance of a Beechcraft B200 aircraft. A fastener hole at the LH forward spar cap had been misdrilled.
With spar cap and strap materials both 0.250" thick and fabricated from 2014-T6511 extrusion and 2024-T351 Alclad plate respectively, precise restoration was essential.
The hole needed to be enlarged to 11/32" to clean up the damage and then returned to the nominal 0.250" diameter to accept standard MS20470AD-8 fasteners. Without a suitable repair, extensive repair and approval activity may have been required
The Old Way: Why Traditional Repairs Create More Problems
When a mis-drilled or elongated fastener hole is identified during routine inspection
or maintenance, a traditional MRO approach might follow these general steps:
- The damaged hole is reamed to a larger size. This removes out-of-round deformation and restores hole geometry. But it also reduces edge distance. That reduction can require engineering disposition before work continues.
- If the oversized hole threatens structural integrity or violates design tolerances, the MRO must request a disposition from the OEM or a DER (Designated Engineering Representative). This review may require reinforcement doublers, custom inserts, or full splice repairs. Each option adds time and cost.
- Once cleared, the oversized hole is reamed and cleaned. An oversized fastener is then wet-installed with corrosion inhibiting compound. Precision is critical. In some cases, tapered reamers or custom tooling are required to maintain alignment.
- After installation, non-destructive testing(NDT) such as eddy current or dye penetrant may be required. Engineering then inspects and signs off on the repair. Notes about inspection intervals or potential impact on fatigue life are often included in the sign-off documentation.
Challenges of this traditional approach:
- Extended repair time from engineering consultation and manual procedures
- Risk of violating edge margins in thin-gauge or precision-fit structures
- Structural compromise from excessive material removal
- Complex logistics involving varied fastener inventories and specialized tooling
- Requirement for follow-on inspections at future maintenance intervals
The PartWorks Solution: A Dual Bushing System That Restores the Original Hole
PartWorks engineers designed a dual bushing repair specifically for situations like this. The goal was simple: clean up the damage, re-center the hole, and allow the aircraft to accept the same standard fastener it was designed for, with no modifications to the surrounding structure.
The system uses two nested bushings installed together:
- An inner bushing made from 15-5PH CRES stainless steel (thin-wall, passivated finish)
- An outer bushing made from 2024-T351 aircraft-grade aluminum (bare finish)
The two bushings sit inside the damaged hole together. These bushings work together to restore proper alignment and reestablish the nominal hole diameter. The system accepts the correct original fastener. Opposing flanges provide structural integrity.
The system is compatible with MS20480AD-8 fastener configurations. Installation uses a specialized mandrel-based process. This process ensures a concentric fit and reliable load distribution across the repair. The bushing goes in at room temperature, straight, concentric, and seated correctly every time. This ensures reliable load distribution.
How PartWorks Proved It Would Work Before Shipping a Single Part
Before any parts went to the field, PartWorks ran two separate validation steps.
Step 1: Computer Analysis (FEA)
PartWorks engineers ran a Finite Element Analysis, a computer simulation that shows how parts behave under load. They modeled how the bushing system would perform during installation, including what happens to the surrounding metal when the bushing expands inside the hole.
• Simulated mandrel pull-through and push-out scenarios
• Evaluated residual hoop stress and radial stress fields
• Analyzed distortion and material displacement under interference fits
Three different fit tolerances were tested to find the right balance between bushing retention (interference) with minimal impact to the structure (deformation or residual stresses). The goal: a bushing that stays put under load without putting excessive stress on the surrounding material.
Step 2: Physical Installation Tests
Test pieces were machined from 7050-T7451 aircraft aluminum. The bushing system was installed under the worst conditions the tolerances allow: bushings too large for the hole, and bushings slightly undersized.
Results across all test conditions:
- All repaired holes accepted standard -4 fasteners with no additional reaming required
- Minimal bushing extrusion at the edges, even at maximum expansion
- No material bulging at the free edge of the hole
- Push-out retention force exceeded 500 lbs in every test
The repair held. The original fastener size was preserved. No follow-up inspections were required.
The Result: Aircraft Back in Service. No Engineering Delays. No Oversized Fasteners.
The PartWorks dual bushing system fixed the mis-drilled hole on the Beechcraft B200 without any of the complications that traditional repairs typically require.
- Standard MS20470AD-8 fasteners used, no oversize inventory needed
- No follow-on inspection intervals added to the maintenance record
- Aircraft returned to service without any impact to fatigue life
"PartWorks delivered a validated, field-ready solution that eliminated the need for engineering delays, specialty tooling, and oversize fastener inventory. The aircraft went back into service without any record of compromised structural integrity."
PartWorks Engineering Team
What This Means for Your Operation
If your shop deals with mis-drilled holes, elongated fastener holes, or damaged fastener locations in structural aircraft components, this repair system was built for exactly that situation.
No exotic materials. No multi-week approval process. No oversized fasteners to stock. Just a clean, tested repair that restores the original hole and gets your aircraft back in the air.
Every hour a grounded aircraft is not flying, it costs money. PartWorks exists to reduce that time.
This case study documents a PartWorks dual bushing repair performed on a Beechcraft B200 aircraft. Engineering analysis and installation validation were conducted by the PartWorks engineering team. Published April, 2026, by Jude Restis.