In order to standardize the grading of aircraft, aircraft appraisers use the following standards when judging aircraft. For continuity, we ask that all aircraft owners use these same standards when describing their aircraft.

Historical data from tens of thousands of appraisals over the past 20 years have shown that, in any category (airframe, paint, and interior), about one-third of all aircraft can be described as rating a "5" ("Average"), with one-third rating between "6" and "10" and the other third rating between "1" and "4".

BE HONEST! Inflating the condition of an aircraft can result in problems with the aircraft qualifying for financing at the resulting inflated purchase price. If the lender requests that an appraisal be conducted, as over 5,000 banks routinely do, and the appraiser's computed value differs significantly from the owner's asking price, the sale could fail.

To convert numerical ratings to phonetic ratings, use this table: 

SUPERFICIAL DAMAGE HISTORY: Slight dings generally associated with hangar rash etc. which have been repaired via replacing damaged areas with new or used serviceable components (Hangar rash, wing-tip caps, wheel pants, plastic etc.). No FAA Form 337 was filed with the FAA.
MINOR DAMAGE HISTORY: Ostensibly minor damage or heavy wear to leading edges of wing, wing-tip, cowling etc. which has been repaired in a manner consistent with manufacturers recommended procedures. No structural components were involved. No FAA Form 337 was filed with the FAA.
MODERATE DAMAGE HISTORY: Extensive damage to components not affecting major structural components. (i.e., gear up landing, fuselage or flight surface skins were repaired or replaced, etc.) An FAA 337 form may or may not have been filed with the FAA.
MAJOR DAMAGE HISTORY: Major structural component damage but replaced with new or used serviceable components and repaired in accordance with manufacturers recommended procedures, (i.e. tail surfaces or wing replaced, wing spar, fire-wall and engine mounts etc.). An FAA 337 form was filed with the FAA and is in the aircraft records.
EXTENSIVE MAJOR DAMAGE HISTORY: Major structural components have been extensively damaged but repaired in accordance with manufacturers recommended procedures. An FAA 337 form was filed with the FAA and is in the aircraft records.

#10 Rating: The airplane is fewer than 5 years old and has lower than average total time. Structural exterior surfaces are absolutely flawless. External surfaces (aluminum, epoxy, wood and fabric) are wrinkle, crease and blemish free. All rivet, stitch or glue lines are straight and even. Rivets are pulled evenly. There are no abnormalities and the aircraft is in flawless, brand new condition with no damage history.
#9 Rating: The airplane is is 1-10 years old and has lower than average total time. Exterior surfaces are almost flawless and would meet the #10 criteria except for 1 or 2 minor exceptions. Example: some rivet’s may be pulled unevenly or some minor nicks around the belly of the aircraft from prop slinging pebbles. The aircraft has had no skin or structural repairs and no damage history.
#8 Rating: The aircraft may be 1-30 years old, but it has lower than average total time. Within 20 feet the aircraft would meet the #9 criteria. On close inspection there may be minor deformations on the underside of aircraft surfaces and minor abrasion on leading edge surfaces. Around cowling fasteners, inspection plates and door entry latch etc., there may be evidence of minor wear and/or abnormalities. It has no history of corrosion and if any damage history exists, the damage would have been minor in nature and the repair is undetectable except for a log entry and FAA Form 337.
#7 Rating: The aircraft is 1-40 years old and has average or greater total time. The airframe shows very well with a few areas of minor dents or deformations. Airframe is corrosion free, however it may have had minor surface corrosion which has been cleaned and corrosion treated and painted. Cowling fasteners may show wear, along with inspection panels, door and cargo door entry areas. Any repairs to airframe were accomplished in a manner that are undetectable and the only physical evidence of repairs are log entries and FAA Form 337’s. Any damage history would not have involved major structural components of the airframe (wing spar etc.). Any hail damage would have been repaired in a manner which is undetectable and to manufacturers recommended procedures.
#6 Rating: Any previous damage to the airframe has been repaired to manufacturers specifications. The areas involved would be damage free and not raise any suspicion upon inspection that the area has previously been damaged. Corrosion history is not extensive and affected surfaces have been repaired and treated. Leading edge surfaces and high use areas such as cowling fasteners, aircraft entry, inspection panels etc. show evidence of wear. Minor cracks in aluminum have been stop drilled and repaired, and the repairs appear to have been successful. Hail damage to flat surfaces are noticeable within 5-7 feet of the aircraft. Any deformations are of a nature which are not a major distraction to the appearance of the aircraft. The aircraft may have moderate to relatively high total time but with a history of regular maintenance documented by logs.
#5 Rating: One out of three aircraft fall into this category. The airframe is structurally sound. Leading edges may show evidence of abrasion wear. Surfaces under the wings, fuselage and gear may show some evidence of nicks and abnormalities from prop slung pebbles etc. Minor surface corrosion may be evident on external surfaces which can easily be repaired by stripping, chemically treating and repainting the affected areas. The flat surfaces may show minor hail damage which would not be noticeable within 20 feet of the aircraft. Aircraft may have sustained damage, but has been repaired in a manner which is consistent with factory recommendations and procedures. There may be a few cracks in the skin which need to be stop drilled. There may be some minor hangar rash type of discrepancies on the airframe which do not affect the safety or flight performance of the aircraft. The aircraft may have total time far above average, but it is airworthy and the overall appearance of the airframe is good.
#4 Rating: The airframe possesses the discrepancies described in #5 Rating but to a larger extent. There are quite a few cracks which need to be stop drilled. Any hail damage is quite noticeable but the airframe is airworthy. However, the overall appearance is poor.
#3 Rating: The airframe is in poor condition and would require maintenance before the aircraft could pass an Annual Inspection. The aircraft has deteriorated to a point that it shouldn't be considered airworthy and continued service would be unwise.
#2 Rating: The aircraft requires very extensive repairs to become airworthy and the extent of repairs is such that the cost may exceed the value of the aircraft.
#1 Rating: The aircraft’s only value is salvage.

EXTERIOR PAINT GRADING INSTRUCTIONS

#10 Rating: The paint is two years old or less. It is flawless in all respects. Painted surfaces have a deep, rich, wet look. There is no pooling, sagging, running, orange peeling, thin areas or over-spray on any painted surfaces. Stripes and numerals are well defined with crisp lines and no irregularities. The paint is of high quality. If a re-paint, all surfaces have been stripped and prepared properly and consistent with the paint manufacturers recommended application procedures.
#9 Rating: The paint may be over 2 years old but fewer than 5 years old if the aircraft is tied down outside or 10 years if old if the aircraft is stored under cover. Exterior painted surfaces are almost flawless. In almost every aspect the painted surfaces would meet the #10 rating criteria except for minor exceptions. There may be a very small amount of dust particles in the paint. There may be a few chips in the paint under the fuselage from props slinging pebbles. The paint looks like new and the above discrepancies are only discernible upon very close inspection.
#8 Rating: The paint is no more than 20 years old. It has a wet look with a few chipped areas under wings, fuselage and empennage. Leading edges may show first stages of abrasion wear but, but a small amount of touchup would fix it. Overall, the paint is in very good condition and shows very well within 20 feet.
#7 Rating: Paint has a good shine with some abrasion wear on leading surfaces but still retaining good coverage. Repainted surfaces or touched up areas are not noticeable. The paint may be new but was a poor job with orange peel, pooling, sags or over-spray. However, painted surfaces are well protected and the aircraft has good eye appeal from more than 20 feet away.
#6 Rating: Paint is beginning to oxidize with evident abrasion wear on leading edges. With touch up and a good cleaning and waxing, paint would have a semi-gloss appearance that would move it into the #7 Rating. If recently painted, it was a very poor job with pooling, sagging, running or orange peeling and/or significant amount of foreign particles in paint. Accent trim may be of poor quality, but paint overall would be adhering well to surfaces. Overall appearance within 30 feet is fair to good.
#5 Rating: Paint is oxidizing and there may be numerous areas of chipping on lower surfaces of aircraft. To bring up to the #6 standard, small areas, such as the leading edges and underside of wings, would need repainting. Leading edges show significant signs of abrasion wear. Surface corrosion may be apparent on the airframe and will affect paint because the painted surface must be stripped in order to treat the corrosion. Overall appearance is fair within 30 feet.
#4 Rating: Consistent with all of the characteristics of #5 rating except the aircraft will soon need repainting, particularly if the aircraft is stored outside. Overall appearance is poor to fair; touch-up and cleaning/waxing will not significantly improve the appearance or protection of the aircraft surfaces. Surface corrosion may be evident in more than a few places.
#3 Rating: Paint is poor quality, heavily oxidized and shows excessive wear on leading edges and control surfaces. Many chips and scratches are apparent, and overall, the aircraft needs painting. However, the paint is protecting most of the aircraft surfaces, but looks poor and would make the aircraft difficult to sell unless significantly discounted.
#2 Rating: Aircraft needs painting. No good points.
#1 Rating: Aircraft needs painting, and additional preparation of the aircraft surfaces is required before painting. Generally consistent with aircraft having extensive corrosion on surfaces.

INTERIOR GRADING INSTRUCTIONS

#10 Rating: Interior condition is new and flawless. All material, fabric, plastic, carpet, headliner, wood cabinetry, etc. are spotless, with no matting, scratches or signs of wear. Seams are straight, tight and in general the interior looks, feels and smells new.
#9 Rating: Interior is 2-3 years new, and has modern styling. It is almost flawless and it would meet the #10 rating criteria except for minor exceptions: Carpet at the entry area and in the cockpit, and perhaps the pilots, and/or the copilots seats, may show slight signs of matting..
#8 Rating: Interior is 3-10 years old and is very clean with no tears, loose stitching, stains, fading or excessive wear on fabric, carpets, plastic, wood cabinetry, or headliner. No plastic pieces are cracked. Any required cleaning involves vacuuming and light shampooing only.
#7 Rating: Interior is no more than 20 years old. It is clean with no tears, major stains or fading or excessive wear on fabric, plastic, wood cabinetry, or headliner. Carpet at entry and cockpit areas may show signs of wear but are not ragged. Stitching of the fabric is tight, although the seams may not be straight. No plastic pieces are cracked and no upholstery repairs have been made in the past nor are needed now. Any required cleaning involves shampooing and light scrubbing by a novice operator, but once completed, the interior would be rated a #8.
#6 Rating: Interior may be original and more than 20 years old. Although the interior has stains which do not clean up, and the overall appearance is clearly "used," in general the interior is in good serviceable condition. The carpets show wear at entry and cockpit areas. One or two plastic pieces are cracked and need replacement. There may be matting of materials on seats with wear noticeable on arm rest and lower seat cushions, but this is less noticeable after steam cleaning and scrubbing. There may be stains on the headliner and/or signs of fading, and there may be evidence of some minor repairs performed in the past.  However, the interior fabric is generally bright and no repairs are currently needed. After a good steam-cleaning and scrubbing, the interior would earn a #7 Rating if no plastic pieces are cracked. The interior condition would not detract institutional buyers and most private buyers if the aircraft was in otherwise good condition.
#5 Rating: Entry areas, cockpit and other high use areas show significant signs of wear and/or stains. Seat cushions, headliner and side panels may have stains, loose stitching, some fading, and in general have a "well used" appearance. More than two plastic pieces are cracked and need replacement. One or two minor repairs to carpet, headliner, and upholstery may be needed. After repairs are made and a professional steam cleaning, scrub, and detail job are performed, the condition may warrant a #6 Rating. If the rest of the aircraft is in good condition, the interior's condition would still appeal to most institutional buyers and all but the most discriminating private buyers.
#4 Rating: Generally the interior has the same characteristics of a #5 rating except  more repairs may be needed and more plastic pieces need replacement. The fabric areas exposed to sunlight are well faded and beginning to dry rot. The only way to improve the appearance of the interior would be to install a new one. However, once repairs are made and the interior cleaned, it would be serviceable for some time. Most private and institutional buyers would shy away from an aircraft with this interior.
#3 Rating: The interior has all the conditions of a #4 rating except numerous repairs are needed. The interior is in poor condition, is no longer serviceable, and would preclude  the aircraft from being sold to a private buyer.
#2 Rating: The interior is not serviceable and the extent of repairs required to make the fabric serviceable would not be cost effective. The interior needs to be replaced and the aircraft will likely not sell until it is.
#1 Rating: Generally all of the characteristics of #2 with the exception of the required repairs include interior structures such as seat frames, chair rails, cabinetry etc..