You tie down after a long cross-country, grab your bags, and on the walk around you notice it: a dark streak running aft from the cowl flaps and exhaust stack, spreading along the belly toward the tail. Every piston airplane does this to some degree. A little oil mist from the breather, exhaust soot, and road-film-like grime from the runway all collect on the underside, where most of us don’t look very often.
Left alone, it gets baked on and harder to remove. It also hides things. A fresh oil leak or a hydraulic weep is much easier to spot on a clean belly than on one that’s already streaked from nose to tail.
Most owners don’t need a bulk drum for this; they need a bottle on the hangar shelf that handles the job in a few minutes after a flight, before the grime has a chance to set.
Quick answer: Aero Cosmetics Belly Soap 16 fl. oz. is a heavy-duty spray-on, wipe-dry cleaner for aircraft bellies and engine areas coated with dried or baked-on hydraulic fluids and oils. It removes grease, oil, hydraulic fluid, and exhaust soot, is safe on wet or dry surfaces, and meets the Exterior BSS7432 specification. Aero Cosmetics part number: 789P. Available on Skyfarer and at Skyfarer Shop.
What it cleans
Belly Soap is a spray-on, wipe-dry product that’s safe on wet or dry surfaces, and Aero Cosmetics lists it as meeting the Exterior BSS7432 specification.
- Aircraft bellies. Including the dirtiest ones, with dried or baked-on hydraulic fluids and oils.
- Engine areas. Grease and oil buildup around the engine compartment.
- Exhaust soot. The dark trail behind the exhaust stack.
- Other vehicles. Also suited to RVs, cars, boats, and motorcycles.
A quick post-flight belly clean
- Let things cool. Give the engine and exhaust time to cool before you reach in near them.
- Spray it on. Apply Belly Soap to the streaked area, working one section at a time.
- Scrub the heavy spots. For the toughest buildup, Aero Cosmetics recommends pairing Belly Soap with the Aero Scrubber.
- Wipe dry. Use towels you don’t mind getting oily, and switch to clean ones as they load up.
Pilot tip: Once the belly is clean, take a photo of it. If a new streak shows up after the next few flights, you’ll know exactly where it’s coming from and can point your mechanic to it, whether it’s a breather, a loose fitting, or something that needs a closer look.
Other sizes and helpful extras
If you clean often or share a hangar, the 32 fl. oz. bottle lasts longer, and shops can step up to the 5-gallon or 55-gallon sizes. For wiping, Aero Towels On A Roll are made for greasy jobs, and the Belt Bottle Holder keeps a 16 oz spray bottle on your hip while you work.
More photos
Where to buy
Aero Cosmetics Belly Soap 16 fl. oz. is sold by Skyfarer Shop. Find it on the Skyfarer marketplace or order directly from Skyfarer Shop. Either link shows the current price. In-stock items ship in 1–3 business days with tracking, U.S. orders over $70 ship free, and most items can be returned within 30 days of delivery.
Frequently asked questions
What does Belly Soap remove?
Grease, oil, hydraulic fluid, and exhaust soot, including dried or baked-on hydraulic fluids and oils.
How do I use it?
Spray it on and wipe it dry. It’s safe to use on wet or dry surfaces.
Can I use it on my car or boat?
Yes. Aero Cosmetics lists it for aircraft, RVs, cars, boats, and motorcycles.
What part number is the 16 oz size?
789P.
