85-24-04 CESSNA AIRCRAFT COMPANY: Amendment 39-5231. Applies to Cessna Model S550 airplanes, Unit Numbers -0001 through -0075, certificated in any category.
Compliance is required as indicated, unless already accomplished.
To prevent hazardous accumulation of ice on the inboard wing leading edge during flight in icing conditions, accomplish the following:
A. Prior to further flight:
1. Fabricate and install on the instrument panel in clear view of the pilot the following placard, using letters of a minimum of 0.10 inch in height: "FLIGHT INTO KNOWN OR FORECAST ICING PROHIBITED" and operate the airplane accordingly.
2. Revise the Airplane Flight Manual, Section II, Operating Limitations - Operations Authorized, to read: "This airplane is approved for day and night, VFR, IFR flight. Flight into known or forecast icing conditions prohibited." This may be accomplished by inserting a copy of this AD in the Airplane Flight Manual.
B. Within the next 15flight hours or 15 days after the effective date of this AD, whichever occurs first, inspect and replace, as necessary, the fluid ice protection system proportioning units as described below:
1. Locate the fluid anti-ice proportioning units as follows:
a. Remove the access panel from the lower surface of the left wing root leading edge fairing to gain access to the left outboard wing proportioning unit.
b. Remove the right wing root leading edge fairing to gain access to the right outboard wing and left and right inboard wing-engine proportioning units.
c. Remove access panel 340BL or 340BR (located below the horizontal stabilizer on the vertical stabilizer) to gain access to the tail proportioning unit.
2. Locate the identification plate installed on each proportioning unit and identify that the correct part number proportioning unit is installed in the proper location (refer to TABLE 1, below).
TABLE 1
PROPORTIONING UNIT PART NUMBER/LOCATIONPART NUMBER
LOCATION
PU306DW38
Left and Right Wing Root
(Left and Right Outboard Wing)
PU306DC39
Right Wing Root
(Left and Right Inboard Wing-Engine)
PU306DT41
Vertical Stabilizer
(Tail)
Refer to Model S550 Maintenance Manual, Revision 30-1, dated May 1, 1985, for detailed installation information.
3. If the correct part number proportioning units are installed in all locations, reinstall all access plates using existing hardware and make an entry in the aircraft maintenance record indicating that the requirements of this AD have been complied with.
4. If the incorrect part number proportioning unit(s) is installed in any location(s), remove and replace the proportioning unit(s) with the correct part number proportioning unit. Refer to the Model S550 Maintenance Manual, Revision 30-1, dated May 1, 1985, Chapter 30, Removal/ Installation Proportioning Unit, for removal and replacement instructions.
C. Within 5 days after the required inspection,report any defects found to the Manager, Wichita Aircraft Certification Office, FAA, Central Region, 1801 Airport Road, Room 100, Mid-Continent Airport, Wichita, Kansas 67209.
D. The requirements of paragraphs A.1. and A.2., above, may be accomplished by the holder of a pilot certificate issued under Part 61 of the Federal Aviation Regulations (FAR) on any airplane owned or operated by him. The person accomplishing these actions must make the appropriate aircraft maintenance record entry as prescribed by FAR 91.173.
E. The requirements of paragraphs A.1. and A.2., above, are no longer required after the requirements of paragraph B. of this AD have been accomplished.
F. Airplanes may be flown in accordance with FAR 21.197 and 21.199 to a location where the inspection/modification requirements of the AD can be accomplished.
G. Alternate means of compliance with this AD which provide an acceptable level of safety may be used if approved by the Manager, Wichita Aircraft Certification Office, FAA, Central Region, 1801 Airport Road, Room 100, Mid-Continent Airport, Wichita, Kansas 67209.
All persons affected by this directive who have not already received the appropriate service documents from the manufacturer may obtain copies upon request to Cessna Aircraft Company, P.O. Box 7704, Wichita, Kansas 67277. These documents also may be examined at FAA, Northwest Mountain Region, 17900 Pacific Highway South, Seattle, Washington, or FAA, Central Region, Wichita Aircraft Certification Office, 1801 Airport Road, Room 100, Mid-Continent Airport, Wichita, Kansas.
This Amendment becomes effective February 24, 1986, as to all persons, except those persons to whom it was made immediately effective by Priority Letter AD 85-24-04, issued December 3, 1985.