74-24-13 UNITED INSTRUMENTS, INC.: Amendment 39-2028. Applies to P/N 5932 ( ) (Serial Numbers 47851 thru 69000) and P/N 5934 ( ) (Serial Numbers 70,000 thru 102,000, A1 thru A9999, B1 thru B9999, and C1 thru C2860) altimeters installed on various aircraft, such as Piper, Beech, Cessna, Bell, Aero Commander, Schweizer, Enstrom, Helio, American Aviation, Bellanca, et al.
Note 1: United Instruments P/N 5932 ( ) altimeters may be additionally identified as TKK Model LA 4 TSO C-10b. United Instrument P/N 5934 ( ) altimeters may be additionally identified as TKK Model LA 7 TSO C10b.
Note 2: These altimeters may also be identified by various aircraft manufacturer's part numbers. Some but not all are:
Beech: P/N 50-380094-( ), 50-384119-( ), 58-380011-( ), 58-380012-( ), 58-380041-( ), 100324056-( ), 169-380073-( )
Cessna: P/N C661011-( ), C661071-( ), C661025-( ), C661014-( )
Piper: P/N 99009-( ), 450-611-( ), 450-694-( ), PS50008-( )-( ), 550-488-( ), 550-489-( ), 550490( ), 550-491-( ), 550-492-( ), 550-493-( ), 322-81-03, 322-81-04
Bell: P/N 206-070-263-( ), 47-711-303-( )
Compliance: Required as indicated, unless already accomplished.
To prevent being deprived of altimeter readings during certain aircraft operating conditions, accomplish the following:
A) Within the next 10 hours' time in service after the effective date of this AD, check each altimeter installed in all aircraft or check the aircraft's permanent maintenance record to determine if the altimeter falls within the Part Number and Serial Number designations set forth in the applicability statement. The owner/operator of the aircraft may make these checks.
B) If, as a result of the determinations required by Paragraph A, an altimeter falls within the Part Number and Serial Number designations in the applicability statement, prior to further flight, either comply with Paragraph C or install a placard on the instrument panel in clear view of the pilot which states:
"AIRCRAFT APPROVED FOR DAY VFR FLIGHT ONLY"
and operate the aircraft in accordance with this limitation.
C) On or before November 30, 1976, on any altimeter which falls within the Part Number and Serial Number designations set forth in the applicability statement, either replace the altimeter with an approved replacement part, an altimeter from outside the applicable Serial Numbers, or modify the existing altimeter in accordance with the United Instruments, Inc., Service Bulletin No. 1, dated September 19, 1974, or subsequent approved revisions. A modified altimeter will be identified by a 1/4-inch white dot painted alongside the nameplate on the back of the case. Upon compliance with this paragraph, the requirements of Paragraph B are no longer applicable.
D) Any alternate means of compliance with this AD must be approved by the Chief, Engineering and Manufacturing Branch, FAA, Central Region.
E) Compliance with Paragraph B of this AD is not required if the aircraft has two sensitive altimeters installed. In the event of failure of one of the altimeters, where both altimeters are noted in the applicability statement, compliance with Paragraph B and/or C is required.
This amendment becomes effective December 5, 1974.