Everything that makes carpet cleaning simple on the ground is prohibited in a cabin
There is more technique in aircraft carpet than in any other cabin surface, because the ordinary tools do not transfer. Solvent spotters containing trichloroethylene or MEK are prohibited on cabin carpet. Full-strength bleach never goes on carpet or fabric, and the Gulfstream completion handbook goes further than that: do not take bleach aboard at all, and never mix ammonia and chlorine bleach. Drying with heat above roughly one hundred degrees Fahrenheit shrinks the carpet, and a shrunk bound carpet does not go back to size. Vacuuming with a beater brush strips fire retardancy out of the fibre, and so does aggressive cleaning generally. Two carpets of the same fibre content can behave differently, which is why anyone working responsibly tests an inconspicuous area before touching the aisle.
Extraction on an aircraft is four controls, not a machine
Controlled moisture, controlled chemistry, controlled dwell, controlled drying. The aim is to lift soil and then get the water back out, rather than soak the pile and push soil down into the backing where it waits. Pre-vacuum without a beater. Test first, because fibre content does not predict behavior. Spot-treat before the general pass, so the general pass is not doing two jobs at once. Then extract with the recovery side carrying the work, and move air through the cabin until the backing is dry and not merely the surface. The floor beneath is structure, not concrete. Water that travels down does not evaporate on its own, and trapped moisture against structure is a corrosion problem rather than a cleaning one.
Both wrong answers are expensive, in different ways
Replace a carpet that was only dirty and you have paid for material, fabrication, fitting and downtime to solve a problem a day of skilled labour would have solved. Worse, if the odour was in the underlayment rather than the fibre, the new carpet smells within a month and you have learned nothing. Go the other way and you spend on extraction for carpet worn through to the backing, which comes back clean and still finished. Cleaning does not restore pile that is gone. The decision is made by inspecting the carpet, not by looking at the stain that prompted the call.
Replacement brings the flammability rule with it
New cabin material is not a decorating choice. On a transport-category aircraft the governing requirement is 14 CFR 25.853 with Appendix F. Material is burn-tested vertically, in the thickness and form in which it is installed, and it has to stay inside the limit on average burn length and inside the fifteen seconds allowed for flame time after the ignition source is removed. That means test documentation, a supplier who can produce it, and lead time. It is not a same-week item, and it is not work a mobile crew does on a ramp. We will tell you when you have reached that point rather than sell you a clean that cannot hold.
What changes the answer
Four things. Where the odour lives, in the fibre or in the underlayment. Whether pile is present or worn to the backing in the aisle and at the galley entry. Whether the carpet has shrunk or lifted at the binding, neither of which is recoverable. And timing. If the interior is going into a refresh within the year, replacement stops being a carpet decision and becomes part of a schedule where the downtime is already committed. A pending sale or a major inspection pulls it forward for the same reason: the aircraft is down anyway.
A quick carpet clean and a cabin extraction are two different products
One person, one machine and one product moving quickly is a domestic carpet clean performed inside an aeroplane. It is a different job from the one a cabin needs, not a thrifty version of the same job. The cabin version begins with a test in an inconspicuous area, because two carpets of the same fibre content behave differently. Chemistry is then chosen per stain and chosen for an enclosed cabin, where 14 CFR 25.831(b) requires the air to be free of harmful concentrations of gases and vapours. Then a general pass with the recovery side carrying the work, then hours of managed drying before anyone signs it off. An over-wet carpet wicks and has to be done again. A heat-dried carpet shrinks, and a shrunk bound carpet is a replacement. A carpet cleaned with the wrong chemistry or a beater brush has lost fire retardancy that cannot be put back. The redo is not the serious loss. The carpet is.