Mandatory Inspection Intervals and Replacement Times for Airborne Check Valve Manifolds

Airborne Air & Fuel Products

Service Letter Number: 39A

Subject: Mandatory Inspection Intervals and Replacement Times for Airborne Check Valve
Manifolds, Check Valves and Regulator Check Valve Manifolds.

Applicability:

All Airborne Check Valve Manifolds, Check Valves and Regulator Check Valve Manifolds. These valves which are listed below are typically installed on single-engine and multi-engine piston aircraft equipped with dual pneumatic power sources to power the gyro flight instruments and de-ice systems.

1H5 Series (all dash numbers)                         — Check Valve Manifolds (Vacuum System)
1H24 Series (all dash numbers) and 2H24-8   — Check Valve Manifolds (Pressure System)
1H37 Series (all dash numbers)                       — Check Valves (Vacuum/Pressure System)
2H3-39 and 2H3-47                                          — Regulator Check Valve Manifolds (Vacuum                                                                               System)

The date of manufacture is encoded on the nameplate of these components. The numbers (1 through 12) indicate the month (January through December) of manufacture. The following letter combinations indicate the year of manufacture:

T = 1972         E = 1979          AB = 1986        AJ = 1993      AT = 2000       BC = 2007
V = 1973         F = 1980          AC = 1987        AK = 1994     AU = 2001       BD = 2008
W= 1974         H = 1981         AD =1988         AL = 1995      AV = 2002       BE = 2009
A = 1975         J = 1982          AE = 1989        AM= 1996      AW= 2003       BF = 2010
B = 1976         K = 1983         AF = 1990        AN = 1997      AY = 2004       BG = 2011
C = 1977         M = 1984        AG = 1991        AP = 1998      BA = 2005       BH = 2012
D = 1978         AA = 1985      AH = 1992        AR = 1999      BB = 2006       BJ = 2013

Mandatory Inspection Intervals*
Beginning five (5) years from date of manufacture, the serviceability of these components must be verified every twelve (12) months in accordance with the procedure provided in the mandatory testing instructions in this document.

Mandatory Replacement Times*
These pneumatic system check valve manifolds, check valves and regulator check valve manifolds must be replaced ten (10) years from date of manufacture.