G450 AMM 57-50-00
GIV AMM 57-50-00
CMP 575019

At West Star Aviation, our Gulfstream specialists have recently experienced several aircraft showing corrosion and cracks within the outboard trailing edge box and wing rebate flange during 24M inspections.

The Computerized Maintenance Program (CMP) Task 575019 & 575020 is required at the 24M Inspection interval on the GIV/G450 aircraft. A borescope is used to inspect the wing plank from edge of rear beam flange to the aft edge of the flange to which trailing edge is attached.

If there are signs of corrosion, then further inspection is required, and the flap, aileron, outboard trailing edge and winglet must be removed to gain access for further evaluation and repair. At this time, there are no Customer Bulletins, Airworthiness Directives or Service Bulletins for this issue.

However, thankfully West Star Aviation has the capability to provide a solution using standard repair processes depending on the level of damage. As an MRO, West Star Aviation must submit findings to Gulfstream Engineering for repair. They will then give a disposition for allowance or repair procedure.

The repair process includes:

• Cut out corroded area(s) per engineering documents.
• Make plaster mold casting and send into repair control.
• Repair control then makes a 3D print as well as first test piece.
• Verify manufactured piece fits as stated in Eng. Documents.
• Resubmit new mold if any defects noted (this process can require multiple molds).
• Once verified, install one-piece CNC-milled doubler on outside of wing skin plank.

Once a repair procedure is completed, an Engineering 8110 is required for return to service.

The severity of the corrosion and cracking observed by West Star Aviation has varied, but in extreme cases, repair labor can range from 650 to 800 hours. West Star has encountered approximately seven instances of this corrosion company-wide (CHA: 4, GJT: 1, ALN: 2).

West Star Aviation can accomplish this inspection and repair at all four full-service facilities (ALN, CHA, GJT and PCD). For more information on this inspection and repair process, please contact any of the specialists listed below: