X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from [207.46.163.181] (HELO na01-bn1-obe.outbound.protection.outlook.com) by logan.com (CommuniGate Pro SMTP 6.0.8) with ESMTPS id 6773662 for lml@lancaironline.net; Thu, 13 Mar 2014 21:53:52 -0400 Received-SPF: pass receiver=logan.com; client-ip=207.46.163.181; envelope-from=rpastusek@htii.com Received: from BY2PR07MB550.namprd07.prod.outlook.com (10.141.217.145) by BY2PR07MB469.namprd07.prod.outlook.com (10.141.220.14) with Microsoft SMTP Server (TLS) id 15.0.898.11; Fri, 14 Mar 2014 01:53:11 +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; Fri, 14 Mar 2014 01:53:10 +0000 From: Robert R Pastusek To: Lancair Mailing List Subject: RE: [LML] L IV maximum speed gear retraction Thread-Topic: [LML] L IV maximum speed gear retraction Thread-Index: AQHPPt0EoTenw+Rcq0qplW5fc6YHCJrfgwnQ Date: Fri, 14 Mar 2014 01:53:09 +0000 Message-ID: <4fd4b07b3699499b81114f051fe9c5cf@BY2PR07MB550.namprd07.prod.outlook.com> References: In-Reply-To: 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: 0150F3F97D x-forefront-antispam-report: SFV:NSPM;SFS:(10019001)(428001)(199002)(189002)(52034003)(19580395003)(59766001)(69226001)(92566001)(83322001)(95416001)(31966008)(19580405001)(33646001)(95666003)(85306002)(81542001)(20776003)(93516002)(63696002)(74366001)(19300405004)(77982001)(46102001)(83072002)(74876001)(51856001)(85852003)(79102001)(81342001)(93136001)(87266001)(87936001)(97186001)(97336001)(74316001)(15202345003)(54356001)(74662001)(56816005)(53806001)(81686001)(47736001)(74706001)(74502001)(94316002)(47446002)(80022001)(65816001)(49866001)(50986001)(16236675002)(15975445006)(47976001)(66066001)(56776001)(81816001)(94946001)(76786001)(80976001)(90146001)(2656002)(86362001)(76576001)(4396001)(54316002)(76482001)(76796001)(24736002);DIR:OUT;SFP:1102;SCL:1;SRVR:BY2PR07MB469;H:BY2PR07MB550.namprd07.prod.outlook.com;FPR:CEFCF014.2F325DE8.DBF55379.4ED4EB61.203A2;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_4fd4b07b3699499b81114f051fe9c5cfBY2PR07MB550namprd07pro_" MIME-Version: 1.0 X-OriginatorOrg: htii.com --_000_4fd4b07b3699499b81114f051fe9c5cfBY2PR07MB550namprd07pro_ Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Bill wote: What happens when the L IV gear is retracted at a speed exceeding the 120 k= ts maximum? Bill, the most common occurrence is that the main gear doors flex closed at= the back due to air loads, and "trap" one or both mains, preventing them f= rom fully retracting. Note that the retraction speed is lower than the exte= nsion speed--I suspect to compensate for the very strong prop blast under t= he airplane during takeoff? If the gear doesn't retract because of this pro= blem, reduce the power, slow down, extend the gear and try it again. If you= suspect other gear problems, I'd put the gear down and if it extends norma= lly, land and check it out. There are some malfunctions that can keep the g= ear from extending. This is not good...but having them hang up on retractio= n should be a minor issue; at most some chipped paint. The gear actually tends to hang on the bolts holding the axle to the gear l= eg, or part of the brake assembly. You can usually tell after landing by th= e chipped paint on the inside of the gear door(s). In any case, the stiffne= ss of the gear doors will have a lot of influence on whether the main(s) ge= t hung up or not. Lancair modified their gear door build plans in about 200= 2 to significantly stiffen them. I incorporated this change and have had no= trouble at all with mine. I tested retraction to 130 KIAS during my Phase = I, but am probably lifting the gear more quickly than I should during norma= l operation, so I don't think I get to 120 before the gear is secure during= normal ops. By the way, I have only one (2 specified) springs on the back = of each main gear door to close it. You didn't ask, but if you fail to re-connect the nose gear door operating = linkage (after replacing the lower cowl?), the nose gear doors will swing s= hut a bit under air loads and trap the nose gear in a partially-retracted p= osition (this one I know from personal experience!) It should extend normal= ly by pushing the doors out of the way in the process. The only fix for thi= s problem is to land and re-attach the linkage. I have not tried, but would= bet money you'll not get the nose gear past the doors, and even if you did= , you'd have the doors flapping in the breeze. By the way, I'm talking about mild exceedence of the published limits above= . If you're talking extending/retracting above 150 KIAS, then I'd think you= could expect damage/loss of the gear doors, and possibly to other aircraft= damage. Bob Pastusek --_000_4fd4b07b3699499b81114f051fe9c5cfBY2PR07MB550namprd07pro_ Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

Bill wote:

What happens when the L IV gear is retracted at a sp= eed exceeding the 120 kts maximum?

 

Bill, the most common = occurrence is that the main gear doors flex closed at the back due to air l= oads, and “trap” one or both mains, preventing them from fully = retracting. Note that the retraction speed is lower than the extension speed--I suspect to compensate for the very strong prop= blast under the airplane during takeoff? If the gear doesn’t retract= because of this problem, reduce the power, slow down, extend the gear and = try it again. If you suspect other gear problems, I’d put the gear down and if it extends normally, land and= check it out. There are some malfunctions that can keep the gear from exte= nding. This is not good…but having them hang up on retraction should = be a minor issue; at most some chipped paint.

 

The gear actually tend= s to hang on the bolts holding the axle to the gear leg, or part of the bra= ke assembly. You can usually tell after landing by the chipped paint on the= inside of the gear door(s). In any case, the stiffness of the gear doors will have a lot of influence on whet= her the main(s) get hung up or not. Lancair modified their gear door build = plans in about 2002 to significantly stiffen them. I incorporated this chan= ge and have had no trouble at all with mine. I tested retraction to 130 KIAS during my Phase I, but am proba= bly lifting the gear more quickly than I should during normal operation, so= I don’t think I get to 120 before the gear is secure during normal o= ps. By the way, I have only one (2 specified) springs on the back of each main gear door to close it.<= /p>

 

You didn’t ask, = but if you fail to re-connect the nose gear door operating linkage (after r= eplacing the lower cowl?), the nose gear doors will swing shut a bit under = air loads and trap the nose gear in a partially-retracted position (this one I know from personal experience!) It should extend norm= ally by pushing the doors out of the way in the process. The only fix for t= his problem is to land and re-attach the linkage. I have not tried, but wou= ld bet money you’ll not get the nose gear past the doors, and even if you did, you’d have the doors = flapping in the breeze.

 

By the way, I’m = talking about mild exceedence of the published limits above. If you’r= e talking extending/retracting above 150 KIAS, then I’d think you cou= ld expect damage/loss of the gear doors, and possibly to other aircraft damage.

 

Bob Pastusek

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