A maintenance visit is a dirty process by design
Panels come off. Lubricants and hydraulic fluid get handled, fasteners get worked, corrosion-inhibiting compound goes back on and leaves a deliberate film, and hands and tools move across the cabin and the leading edges for days. None of that is carelessness. It is the job, done properly. What it means for you is that a finish delivered on Monday is not the finish anyone sees on Friday. Detailing an aircraft to a high standard and then handing it to a maintenance team is buying finish work that gets undone within a day of the shop starting.
Cleaning before the event is access work, and it earns its place
This is the half owners tend to skip, and it is the half with an engineering case behind it. Accumulated belly soil, meaning hydraulic fluid, fuel, exhaust soot and grease, traps corrosive material against structure and makes the attack worse. It also hides precisely what an inspector is looking for: weeping seals, chafing, cracking and fastener condition. A belly and gear degrease before an inspection turns a survey of grime into a survey of metal, which is the point of the inspection. FAA AC 43-4B, the governing corrosion control guidance, treats washing to remove acidic airborne contaminants as corrosion control in its own right, and it leaves inspection frequency and treatment with the operator rather than with whoever happens to have the aircraft.
Why the finish work waits for the panels to go back on
Correction is subtractive. An aerospace clearcoat builds to roughly two to two and a half mils dry film thickness, and every correction spends part of it. That film cannot be replaced without a strip and repaint, which is typically five to seven weeks out of service. So correcting a finish before a maintenance visit, watching a stand mark go into it, and correcting again afterwards does not cost you twice in money alone. It costs you twice in a consumable that cannot be bought back. Coatings fail the same test from the other end: a ceramic cures to the surface it is given, and a fortnight of solvent-bearing hands and tape residue is not that surface.
A wash and a detail are not the same product
The pre-event degrease and the post-event detail are two different products, not a small version and a large version of one. The degrease is access work: belly, gear bays, gear doors and the exterior, one crew working one problem with one class of product, done so that surfaces can be seen. The detail is crew-days in which the cabin is treated as a set of separate materials. Gulfstream's own completion center maintenance handbook carries separate procedures at 12-26-00 for wood, granite, Lexan, vinyl laminate, plating, stainless steel, leather, vinyl, rubber matting, carpet and fabric. Eleven materials, eleven methods. The same chapter warns that a silicone-based polish leaves an oily residue on the urethane wood finish that can prevent a later repair to that finish. That is the distance between cleaning an aircraft and detailing one, and it is why the second one is booked for after the shop has finished.
The failure mode of choosing wrong
The expensive mistake is the full detail booked into the week before induction, usually because that is where the schedule had a gap. The aircraft goes into the shop immaculate and comes out with handprints on the headliner, boot marks on the carpet, a smear of hydraulic fluid down a flap fairing and a stand scuff on a leading edge. A wash fixes the first three. It does not fix the fourth, and the fourth needs machine work on a film with a finite thickness. The sequence that looked efficient is the one that spends clearcoat twice.
What changes the answer
A short, clean, one-item visit where nothing substantial comes off the aircraft and no fluids are handled is the honest exception, and you can wash it whenever suits you. Paint or interior work in the shop changes the answer too, because correction and protection belong after the new finish has cured, on the paint shop's timeline rather than yours. Hangar availability matters as well: correction and coating want a controlled space, and if the only hangar slot sits inside the visit, the sequence has to be negotiated with the shop rather than assumed. An aircraft going from the shop to a sale viewing or a charter debut still gets detailed afterwards, booked against the real release date.
Split the scope deliberately
Two scopes, one decision. Degrease and wash into the event, detail out of it, and do not let anyone persuade you that a single visit can serve both purposes. Book the post-event work against the actual release rather than the promised one, because shops run over and the item that gets compressed is always the finish work. Then take a photographed walk-round at induction and another at collection. Defects introduced during the visit are easiest to identify and attribute while everyone still remembers who touched what, and a dated set of photographs is the difference between a conversation and an argument.