Unbelieveable, whta some people interpret into manuals and documents.
ICAO "Clean Aircraft Concept" states clearly that no aircraft shall be operated with "adhering contamination" to the critical surfaces. This includes definitely on all aircraft types the upper wing surface.
The B737NG is the only aircraft type with an exemption. It is possible to operate this model with a thin layer of frost in a clearly defined area of the upper wing (Service Letter shows the exact dimensions). The maximum thickness is 1/16" and to use this opetion requires two items:
- a modification in form of a amrking on the upper wing area
- AFM must included this scenario
No special FAA approval is required, as the AFM must be approved my your FAA representative.
To the SAAB: It does not differ to any other aircraft model (except B737NG): No contamination on the upeprwing surface. Lower wing surface a maximum of 3mm frost (some aircraft models are even not approved for this) and frost on the fuselage as long as markings, door seals and so on are visible. No other contamination type approved.
Using fluids, esepcially which type, depends on the approval of the airframe manufacturer. Basically you can go back and take the FAA document "Hold-Over-Time Tables for Winter Season 2009/2010" and find all fluids, where the manufacturer has submitted the certification documents acc. SAE AMS 1424 (Type I) and SAE AMS 1428 (Type II/III/IV) to the FAA Tech Center.
A lot of airframe manufacturers, especially business jet producers, have brand names listed in their AMM's (chapter 12-30/31), which are very often outdated. Therefore produce your own list and get your winter ops program acc. FAR 121.621 approved.