Return-Path: Sender: (Marvin Kaye) To: lml@lancaironline.net Date: Mon, 05 Jan 2004 21:58:58 -0500 Message-ID: X-Original-Return-Path: <5zq@cox.net> Received: from lakemtao01.cox.net ([68.1.17.244] verified) by logan.com (CommuniGate Pro SMTP 4.1.8) with ESMTP id 2918712 for lml@lancaironline.net; Mon, 05 Jan 2004 21:30:15 -0500 Received: from OFFICE ([68.110.249.147]) by lakemtao01.cox.net (InterMail vM.5.01.06.05 201-253-122-130-105-20030824) with SMTP id <20040106023015.DYNC23168.lakemtao01.cox.net@OFFICE>; Mon, 5 Jan 2004 21:30:15 -0500 X-Original-Message-ID: <00aa01c3d3fc$fefa1f10$6501a8c0@OFFICE> From: "Bill&Sue" <5zq@cox.net> X-Original-To: "Lancair Mailing List" X-Original-Cc: References: Subject: Re: [LML] Hobbs Meter X-Original-Date: Mon, 5 Jan 2004 21:30:02 -0500 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1158 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1165 The ol' hobbs or the new-fangled SFS timer? Or are both equally as good? Hello Ron, The hobbs meter is usually controlled by an oil pressure switch. It basically tells you how long the engine has been running. This, in itself, is somewhat useless information. Time In Service is what is used to keep track of engine and airframe time. T.I.S. is defined as the time the aircraft leaves the surface of the earth until it touches down again, the time that the airplane is actually in the air. Most GPS's have this feature and it is based on the time that the unit reaches a certain speed (usually 60 knots) until it slows below this speed. This feature is an extremely close approximation of Time in Service. Flight Time is defined as the time the aircraft moves under it's own power FOR THE PURPOSE OF FLIGHT until it comes to rest again after landing. This includes taxi time. Flight Time is the time that you put in your pilot logbook. Hobbs time is a very rough approximation of flight time but probably no better than estimating your taxi time and adding it to your T.I.S. There is no other use for hobb's time unless you're renting your airplane out which is, as we know, not allowed for experimental aircraft under almost all circumstances. Also, when you start the airplane up just to taxi over to the gas pump, the hobbs runs. This time is neither Flight Time nor Time In Service. My opinion is that, in our non-rental environment, the hobbs meter is probably not worth the expense, weight, panel room, installation effort or electricity that it uses. A rough estimate of your taxi time added to the SFS timer's number is probably closer to the "official" flight time definition for your pilot log book. Assuming that the SFS timer retains a cumulative total, it should be extremely close Time In Service. That should be all you need. Excuse my long winded answer to your question. Hope that this helps. Bill Harrelson 5zq@cox.net N5ZQ LNC2 Dogwood Airpark, Fredericksburg, VA