Return-Path: Received: from fed1rmmtao06.cox.net ([68.230.241.33] verified) by logan.com (CommuniGate Pro SMTP 4.2.5) with ESMTP id 549818 for flyrotary@lancaironline.net; Mon, 29 Nov 2004 13:05:32 -0500 Received-SPF: none receiver=logan.com; client-ip=68.230.241.33; envelope-from=ALVentures@cox.net Received: from BigAl ([68.107.116.221]) by fed1rmmtao06.cox.net (InterMail vM.6.01.04.00 201-2131-117-20041022) with ESMTP id <20041129180503.OIXO29028.fed1rmmtao06.cox.net@BigAl> for ; Mon, 29 Nov 2004 13:05:03 -0500 From: "Al Gietzen" To: "'Rotary motors in aircraft'" Subject: EM2 calibration Date: Mon, 29 Nov 2004 10:05:16 -0800 Message-ID: <000001c4d63d$fb365e90$6400a8c0@BigAl> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0001_01C4D5FA.ED131E90" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6626 Importance: Normal In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 This is a multi-part message in MIME format. ------=_NextPart_000_0001_01C4D5FA.ED131E90 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable =20 Since your temps are much higher than before, I would submit that it's likely that either you're previous temp readings were wrong, or your = current ones are, particularly in regard to "negative" oil pressures. I think = you need to be very sure you're EM-2 is calibrated, and not by just matching = one number to a gauge. Check a low, mid, and high level to make sure the = EM-2 is correctly calibrated.=20 Agreed. I wish I knew an easy way to do that. =20 John; Maybe no easy way; but I=92d also recommend checking calibration; = although my oil pressure using the VDO sensor from Tracy seemed to be quite close = based on reading -2 at 0 and a max of about 100, which is the setting of the = RB relief valve. I think I have recalibrated about every channel except the thermocouples; and changed some just a wee bit, and some a lot. In two cases I had different senders. It seems the calibration is installation dependant.=20 =20 Here=92s the procedure I used, and Tracy can alert us if I=92m leading = you astray. Borrow (or buy) an infrared pyrometer (temp gun) for easy = checking of oil and coolant temps. Paint about a 1=94 circle of flat black paint = on surfaces that you want to measure, and hold the gun right up against, = maybe a 1/8 to =BC=94 away for consistent accurate readings. Set the low end = offset at about 120-130F and set the sensor offset equal to the ADC readout at = that point. Adjust the scale factor to get the correct high end reading at = about 210F. Repeat the same points again. You may have to adjust the sensor offset, and the scale factor a bit.=20 =20 For OAT and other aux air temps, use a water container (a coffee mug = works good) and a good thermometer. For OAT, use some ice to get a water temp = down to 40F or less to set low end offset and sensor offset, and some warm = water to set the scale factor to get the high end correct at about 100. Put = the tip of the air temp sensor in the water. For higher temp ranges like = rad air outlet, maybe set the range from about 70F to 150-160F. For = whatever reasons I found the air temps with the RWS senders and the =93stock=94 calibration factors to be considerably off away from the 80F range. Is = the OAT used for TAS and pressure altitude calcs? If so you=92d like to = have that pretty close. =20 For the fuel pressure, coolant pressure and manifold pressure I got some = 2 =96 2 =BC=94 +- 2% gauges from McMaster-Carr for less than $10 each; 0-60 = psi for fuel and -30=94 hg to 15 psi for MAP. For calibrating MAP I used the = local pressure (engine off) for setting the low-end offset, and set scale = factor to get good reading at around 12=94 hg. (it=92s a vacuum gauge, so MAP = is local pressure minus the vacuum reading). For local pressure, I guess you can = use the pressure read in the pressure window on your altimeter needed to = read an altitude of 0; or get the local barometric pressure, which is corrected = to sea level and 60F, and adjust it to your altitude and temperature = (remember that old flight computer?). Be sure the EC2 is on when doing the =93low = end=94 with engine off. My MAP reading was off by 3=94 hg at local pressure of 29.8=94before recalibrating. =20 Maybe it=92s just me, but before I ever role down the runway I want to = know that I have good data. =20 Al =20 ------=_NextPart_000_0001_01C4D5FA.ED131E90 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Message

 

Since your temps = are much higher than before, I would submit that it's likely that either you're = previous temp readings were wrong, or your current ones are, particularly in = regard to "negative" oil pressures.  I think you need to be very = sure you're EM-2 is calibrated, and not by just matching one number to a gauge.  Check a low, mid, and high level to make sure the EM-2 is correctly calibrated. 

Agreed. I wish I = knew an easy way to do that.

 

John;

Maybe no easy way; but I’d = also recommend checking calibration; although my oil pressure using the VDO sensor from = Tracy seemed to be = quite close based on reading -2 at 0 and a max of about 100, which is the = setting of the RB relief valve. I think I have recalibrated about every channel = except the thermocouples; and changed some just a wee bit, and some a lot. =A0In = two cases I had different senders.=A0 It seems the calibration is installation = dependant.

 

Here’s the procedure I = used, and Tracy can alert us = if I’m leading you astray. =A0Borrow (or buy) an infrared pyrometer (temp gun) = for easy checking of oil and coolant temps.=A0 Paint about a 1” circle of flat black = paint on surfaces that you want to measure, and hold the gun right up against, = maybe a 1/8 to =BC” away for consistent accurate readings. =A0Set the low end = offset at about 120-130F and set the sensor offset equal to the ADC readout at = that point.=A0 Adjust the scale factor to get the correct high end reading at = about 210F. Repeat the same points again.=A0 You may have to adjust the sensor = offset, and the scale factor a bit.

 

For OAT and other aux air temps, = use a water container (a coffee mug works good) and a good thermometer. For OAT, use = some ice to get a water temp down to 40F or less to set low end offset and = sensor offset, and some warm water to set the scale factor to get the high end = correct at about 100. Put the tip of the air temp sensor in the water.=A0 For = higher temp ranges like rad air outlet, maybe set the range from about 70F to = 150-160F.=A0 For whatever reasons I found the air temps with the RWS senders and the = “stock” calibration factors to be considerably off away from the 80F range. = =A0Is the OAT used for TAS and pressure altitude calcs?=A0 If so you’d like to = have that pretty close.

 

For the fuel pressure, coolant = pressure and manifold pressure I got some 2 – 2 =BC” +- 2% gauges = from McMaster-Carr for less than $10 each; 0-60 psi for fuel and -30” = hg to 15 psi for MAP.=A0 For calibrating MAP I used the local pressure (engine = off) for setting the low-end offset, and set scale factor to get good reading at = around 12” hg. (it’s a vacuum gauge, so MAP is local pressure minus = the vacuum reading). =A0For local pressure, I guess you can use the pressure = read in the pressure window on your altimeter needed to read an altitude of 0; = or get the local barometric pressure, which is corrected to sea level and 60F, = and adjust it to your altitude and temperature (remember that old flight = computer?).=A0 Be sure the EC2 is on when doing the “low end” with engine = off. My MAP reading was off by 3” hg at local pressure of = 29.8”before recalibrating.

 

Maybe it’s just me, but = before I ever role down the runway I want to know that I have good = data.

 

Al

 

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