X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from [207.46.163.209] (HELO na01-bl2-obe.outbound.protection.outlook.com) by logan.com (CommuniGate Pro SMTP 6.0.8) with ESMTPS id 6768120 for lml@lancaironline.net; Mon, 10 Mar 2014 09:49:07 -0400 Received-SPF: pass receiver=logan.com; client-ip=207.46.163.209; envelope-from=rpastusek@htii.com Received: from BY2PR07MB550.namprd07.prod.outlook.com (10.141.217.145) by CO1PR07MB235.namprd07.prod.outlook.com (10.141.71.11) with Microsoft SMTP Server (TLS) id 15.0.893.10; Mon, 10 Mar 2014 13:48:16 +0000 Received: from BY2PR07MB550.namprd07.prod.outlook.com ([10.141.217.145]) by BY2PR07MB550.namprd07.prod.outlook.com ([10.141.217.145]) with mapi id 15.00.0883.010; Mon, 10 Mar 2014 13:48:16 +0000 From: Robert R Pastusek To: Lancair Mailing List Subject: IV-P Landing Gear Thread-Topic: IV-P Landing Gear Thread-Index: Ac88XiR/gXE2HNcrT4qMDD18cpjZNw== Date: Mon, 10 Mar 2014 13:48:15 +0000 Message-ID: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [108.28.164.93] x-forefront-prvs: 014617085B x-forefront-antispam-report: SFV:NSPM;SFS:(10019001)(428001)(199002)(189002)(52034003)(83322001)(74366001)(97336001)(54356001)(50986001)(47976001)(16236675002)(47736001)(80022001)(65816001)(74876001)(83072002)(81816001)(81686001)(85852003)(51856001)(90146001)(46102001)(19580395003)(49866001)(4396001)(53806001)(94316002)(87266001)(76482001)(54316002)(97186001)(56816005)(56776001)(76176001)(95416001)(19580405001)(63696002)(76576001)(87936001)(74502001)(47446002)(95666003)(94946001)(69226001)(81542001)(77982001)(80976001)(15202345003)(66066001)(59766001)(74706001)(93516002)(15975445006)(33646001)(92566001)(79102001)(19300405004)(85306002)(93136001)(76796001)(76786001)(31966008)(74662001)(86362001)(81342001)(74316001)(2656002)(24736002);DIR:OUT;SFP:1102;SCL:1;SRVR:CO1PR07MB235;H:BY2PR07MB550.namprd07.prod.outlook.com;CLIP:108.28.164.93;FPR:EEC4F2F5.8FFA9B89.41D79D7B.5EF8C961.2057F;PTR:InfoNoRecords;A:1;MX:1;LANG:en; received-spf: None (: htii.com does not designate permitted sender hosts) Content-Type: multipart/alternative; boundary="_000_d3437e5f61a14e1a8bb9f2592c53582eBY2PR07MB550namprd07pro_" MIME-Version: 1.0 X-OriginatorOrg: htii.com --_000_d3437e5f61a14e1a8bb9f2592c53582eBY2PR07MB550namprd07pro_ Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Gentlemen, Without reflecting on the cause of the most recent IV-P loss, I was asked t= o review the operating principles of the Lancair IV landing gear system for= those of you that did not build your airplane. Hopefully this knowledge wi= ll help you if you should have difficulty with the landing gear--which, by = the way, has a different operating principle from the Legacy and 3-series a= ircraft. The landing gear in the IV-P is hydraulically operated by an electric power= pack (a pump/reservoir assembly commonly used to control boat lift/tilt ou= t-drives). Hydraulic fluid is circulated from the pump to a gear/flap contr= ol on the center vertical instrument console in the cabin. The gear handle = is actually a hydraulic valve that switches fluid flow between the "up" and= "down" sides of hydraulic actuators that are attached to the two mains and= the nose gear. With the landing gear handle in the UP position and the hydraulic system pr= essurized, all three gear are retracted and held up by the pressure. There = are no up-latches. If you lose hydraulic pressure in the system for any rea= son, the mains will "free-fall" to a partially-extended "trailing" position= but will not fully extend because they must move forward (against an air l= oad) to do so. NO AMOUNT of maneuvering, touch and go, or flying around wil= l fully extend the mains, and they WILL fold back into the gear bays at tou= chdown if partially extended. No exceptions. The only way to fully extend t= he gear is to apply hydraulic pressure to them, either by restoring the ele= ctrical pump to normal operation, or by use of the hand pump between the fr= ont seats to manually pump fluid into the main gear actuators. There are se= veral things that need to work correctly for this to happen, so emergency g= ear extension--both on jacks and in-flight-- should be one of your required= condition inspection items. The nose gear is equipped with an air spring that causes it to extend fully= if hydraulic pressure is lost. Once extended, it can only be retracted by = restoring normal hydraulic pressure with the gear handle in the up position= . The emergency pump applies pressure only to the down side of the main act= uators; it does not supply fluid to the nose gear actuator in any circumsta= nce. So to repeat, with a loss of hydraulic pressure, you'll get an "automa= tic" nose gear fully extended, and "trailing" mains. The hand pump should b= e able to fully extend the mains, allowing them to lock down automatically,= but if it doesn't, the mains WILL retract on landing. There are no known a= lternatives or exceptions. By the way, if you can get the mains fully exten= ded (green down lights), the actuators have built-in locks that should hold= them fully extended, even if hydraulic pressure to the actuators is subseq= uently lost. Even so, if one or both of the main gear indicator lights shou= ld go out, consider a final tug on the emergency pump just before landing. = If it can be pumped, do so; if it doesn't move, you should still have fully= extended mains. For me, any un-commanded extension of the landing gear would be time to put= the airplane on the ground and sort out the electrical and/or hydraulic pr= oblem--for several reasons. As an example, a hydraulic leak can dump all th= e fluid overboard quickly, and allow the pump to run continuously. In time,= it will destroy itself, and has been known to catch fire--it's not designe= d for continuous operation. One other thought. Flying by the tower, or even having another airplane loo= k you over for extended gear is probably a waste of time, and may give you = a false sense of security. Unless the observer is familiar with the IV lan= ding gear system, he/she is unlikely to identify the difference between mai= ns that are fully extended forward and those in the trail position. They wi= ll note that the nose gear looks good (it should be), conclude that the mai= ns are also "extended," and report that. Lastly, the gear handle has an electro/mechanical "lock" built into it that= SHOULD prevent it being moved out of the down position when the airspeed i= s below about 90 Kts (this is adjustable, so it could be more or less). If = you move the handle to UP when the airplane is on the ground and the hydrau= lic system is pressurized, the weight of the aircraft SHOULD prevent the ma= ins from retracting, but the nose gear will definitely retract, dumping the= nose and prop on the ground. Your checklist does require you to check that= the gear lever is in the down position before applying power to the aircra= ft, doesn't it? Landing gear malfunctions are serious, and can result in major damage to yo= ur airplane even in the best of circumstances. They should not, however, ki= ll or injure you or your passengers if you apply your training and keep you= r cool. Lancairs fly well in any known landing gear configuration. So task = #1 is always to fly the airplane to the scene of the crash...always. I'd be pleased to talk to any of you either on- or off-line about this. Jus= t drop me a note. Bob Pastusek --_000_d3437e5f61a14e1a8bb9f2592c53582eBY2PR07MB550namprd07pro_ Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

Gentlemen,

Without reflecting on the cause of the most recent IV-P loss, I was a= sked to review the operating principles of the Lancair IV landing gear system for those of you that did not build your airplane. Hop= efully this knowledge will help you if you should have difficulty with the = landing gear--which, by the way, has a different operating principle from t= he Legacy and 3-series aircraft.

The landing gear in the IV-P is hydraulically operated by an electric= power pack (a pump/reservoir assembly commonly used to control boat lift/tilt out-drives). Hydraulic fluid is circulated from the pump to= a gear/flap control on the center vertical instrument console in the cabin= . The gear handle is actually a hydraulic valve that switches fluid flow be= tween the “up” and “down” sides of hydraulic actuators that are attached to the two mains and the nose gea= r.

With the landing gear handle in the UP position and the hydraulic sys= tem pressurized, all three gear are retracted and held up by the pressure. There are no up-latches. If you lose hydraulic pressure i= n the system for any reason, the mains will “free-fall” to a pa= rtially-extended “trailing” position but will not fully extend = because they must move forward (against an air load) to do so. NO AMOUNT of maneuvering, touch and go, or flying around will fully= extend the mains, and they WILL fold back into the gear bays at touchdown = if partially extended. No exceptions. The only way to fully extend the gear= is to apply hydraulic pressure to them, either by restoring the electrical pump to normal operation, or b= y use of the hand pump between the front seats to manually pump fluid into = the main gear actuators. There are several things that need to work correct= ly for this to happen, so emergency gear extension--both on jacks and in-flight-- should be one of your requir= ed condition inspection items.

The nose gear is equipped with an air spring that causes it to extend= fully if hydraulic pressure is lost. Once extended, it can only be retracted by restoring normal hydraulic pressure with the gear han= dle in the up position. The emergency pump applies pressure only to the dow= n side of the main actuators; it does not supply fluid to the nose gear act= uator in any circumstance. So to repeat, with a loss of hydraulic pressure, you’ll get an “auto= matic” nose gear fully extended, and “trailing” mains. Th= e hand pump should be able to fully extend the mains, allowing them to lock= down automatically, but if it doesn’t, the mains WILL retract on landing. There are no known alternatives or exceptions. By the way, if = you can get the mains fully extended (green down lights), the actuators hav= e built-in locks that should hold them fully extended, even if hydraulic pr= essure to the actuators is subsequently lost. Even so, if one or both of the main gear indicator lights should go = out, consider a final tug on the emergency pump just before landing. If it = can be pumped, do so; if it doesn’t move, you should still have fully= extended mains.

For me, any un-commanded extension of the landing gear would be time = to put the airplane on the ground and sort out the electrical and/or hydraulic problem--for several reasons. As an example, a hydraulic = leak can dump all the fluid overboard quickly, and allow the pump to run co= ntinuously. In time, it will destroy itself, and has been known to catch fi= re--it’s not designed for continuous operation.

One other thought. Flying by the tower, or even having another airpla= ne look you over for extended gear is probably a waste of time, and may give you a false sense of security.  Unless the observer is familiar with the IV landing gear system, he/= she is unlikely to identify the difference between mains that are fully ext= ended forward and those in the trail position. They will note that the nose= gear looks good (it should be), conclude that the mains are also “extended,” and report that.<= o:p>

Lastly, the gear handle has an electro/mechanical “lock” = built into it that SHOULD prevent it being moved out of the down position when the airspeed is below about 90 Kts (thi= s is adjustable, so it could be more or less). If you move the handle to UP= when the airplane is on the ground and the hydraulic system is pressurized= , the weight of the aircraft SHOULD prevent the mains from retracting, but the nose gear will definitely retra= ct, dumping the nose and prop on the ground. Your checklist does require yo= u to check that the gear lever is in the down position before applying powe= r to the aircraft, doesn’t it?

Landing gear malfunctions are serious, and can result in major damage= to your airplane even in the best of circumstances. They should not, however, kill or injure you or your passengers if you apply yo= ur training and keep your cool. Lancairs fly well in any known landing gear c= onfiguration. So task #1 is always to fly the airplane to the scene of the = crash…always.

I’d be pleased to talk to any of you either on- or off-line abo= ut this. Just drop me a note.

Bob Pastusek

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