december 2011 volume 11 • number 12 - American Bonanza Society

www.bonanza.orgInstrumentAir PressureFilter in anE33ABy Darrell ShyMy issue started when I sent mydirectional gyro in for repair. The techcalled back and said they could repair it,but they could not guarantee it wouldwork due to the carbon in the back of the instrument.He said I needed to change the filter in my E33A’sinstrument air pressure system. I checked the systemand discovered it had a filter at the intake but did(ABS has a copy of the approval information if you have an E33 orE33A needing this documentation. —Ed.)not have an inline filter.I purchased and installed an inline filter from AeroTech Components. At my annual inspection I asked mymechanic to sign off the install. He stated he could notapprove the installation because it was not approved formy airplane (serial number CE-182).I then contacted Ralph Heysek of Aero Tech in Reno,Nevada (775-329-4028). Ralph told me Beech changed froma “wet” pump instrument system to an Airborne “dry” pumpsystem in mid-1967 for the E33 (starting with CD-1119) andE33A (starting with CE-180) but retained the hard aluminumtubing for the system. The Airborne 212CW air pump and1H30-9 pressure regulator became standard equipment onall E33A aircraft.Ralph said that Beech made a modification and added aninline filter after receiving complaints about carbon in theinstruments. This change was done starting on CE-298 inmid-1969. This model was designated as Beech Model F33A.Ralph stated my gyro instrument is basically identicalin construction and operation to the system installed inthe F33A Bonanza. He included drawings and the FAA-PMA Approval Letter indicating that the CV1J4 inline filteris an approved replacement for the Airborne 1J4-6 or 1J4-7inline filter.Ralph Heysek was very knowledgeable and helpful inmy situation. With the paperwork provided by Ralph, myIA was happy to sign the work off.Over 50 yearsBeech experiencePre-Buy and Annual InspectionsNow Offering AmSafe Seatbelt Airbag InstallationsSpecializing in:• Custom Engine Installations• Altimeter and Transponder Certification• Tip Tank InstallationKalamazoo Aircraft Inc.Aircraft Maintenance - Inspection & Repair2729 E. Milham Rd., Kalamazoo, MI 49002 • 269-381-0790www.kalamazooaircraft.com / Repair Station K9AR289NVolume 11 • Number 12 AMERICAN BONANZA SOCIETY 65