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To:  lml@lancaironline.net
Date: Wed, 23 Jul 2014 07:36:39 -0400
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From: Chris Zavatson <chris_zavatson@yahoo.com>
Reply-To: Chris Zavatson <chris_zavatson@yahoo.com>
Subject: LNC2 (outback) flap torque tube corrosion
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I have been finding corrosion inside the flap torque tubes of 320/360s desp=
ite all of them living in a low humidity part of the country.=A0 I first no=
ticed this on my own 360 some 14+ years ago.=0AThe plating on the inside of=
 the torque tube does not adhere very well.=A0 Since the tubes are capped i=
n the center there is no cross ventilation.=A0 Any moisture or water that g=
et into the tube cannot easily escape.=A0 This combination makes the tubes =
prime candidates to corrosion.=0AThe biggest concern is the weld at the ver=
y end of the tube.=A0 The greatest load on this part occurs at full flaps.=
=A0 The most likely failure mode would be one flap suddenly retracting duri=
ng a landing approach.=0A=0AInspecting the interior of this tube should be =
on everyone's annual condition inspection checklist.=0A=0AA few mitigation =
steps are possible if corrosion is found or suspected.=0A=0A1.=A0 Wiping th=
e interior with a corrosion inhibitor such as LPS3 or ACF50 during every an=
nual.=A0 This can be done with a rag or towel secured to a long rod.=A0 =0A=
=0A2.=A0 Coating the interior with a white (white for easy inspection) epox=
y paint.=A0 A rotary wire brush on the end of a long rod will help remove a=
ll of the loose plating and corrosion prior to painting.=0A=0AAlso, drillin=
g the end-plates to form a through hole will enable cross ventilation to re=
move rain or other moisture that finds its way into the tube.=0A=0Abe safe =
out there,=0A=0AChris Zavatson=0AN91CZ=0A360std=0Awww.N91CZ.net=0A
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<html><body><div style=3D"color:#000; background-color:#fff; font-family:ti=
mes new roman, new york, times, serif;font-size:14pt"><div>I have been find=
ing corrosion inside the flap torque tubes of 320/360s despite all of them =
living in a low humidity part of the country.&nbsp; I first noticed this on=
 my own 360 some 14+ years ago.</div><div>The plating on the inside of the =
torque tube does not adhere very well.&nbsp; Since the tubes are capped in =
the center there is no cross ventilation.&nbsp; Any moisture or water that =
get into the tube cannot easily escape.&nbsp; This combination makes the tu=
bes prime candidates to corrosion.</div><div>The biggest concern is the wel=
d at the very end of the tube.&nbsp; The greatest load on this part occurs =
at full flaps.&nbsp; The most likely failure mode would be one flap suddenl=
y retracting during a landing approach.</div><div><br></div><div>Inspecting=
 the interior of this tube should be on everyone's annual condition
 inspection checklist.<br></div><div>A few mitigation steps are possible if=
 corrosion is found or suspected.<br></div><div>1.&nbsp; Wiping the interio=
r with a corrosion inhibitor such as LPS3 or ACF50 during every annual.&nbs=
p; This can be done with a rag or towel secured to a long rod.&nbsp; <br></=
div><div>2.&nbsp; Coating the interior with a white (white for easy inspect=
ion) epoxy paint.&nbsp; A rotary wire brush on the end of a long rod will h=
elp remove all of the loose plating and corrosion prior to painting.<br></d=
iv><div>Also, drilling the end-plates to form a through hole will enable cr=
oss ventilation to remove rain or other moisture that finds its way into th=
e tube.</div><div><br></div><div style=3D"color: rgb(0, 0, 0); font-size: 1=
8.6667px; font-family: times new roman,new york,times,serif; background-col=
or: transparent; font-style: normal;">be safe out there,</div><div style=3D=
"color: rgb(0, 0, 0); font-size: 18.6667px; font-family: times new
 roman,new york,times,serif; background-color: transparent; font-style: nor=
mal;"><br></div><div style=3D"color: rgb(0, 0, 0); font-size: 18.6667px; fo=
nt-family: times new roman,new york,times,serif; background-color: transpar=
ent; font-style: normal;">Chris Zavatson</div><div style=3D"color: rgb(0, 0=
, 0); font-size: 18.6667px; font-family: times new roman,new york,times,ser=
if; background-color: transparent; font-style: normal;">N91CZ</div><div sty=
le=3D"color: rgb(0, 0, 0); font-size: 18.6667px; font-family: times new rom=
an,new york,times,serif; background-color: transparent; font-style: normal;=
">360std</div><div style=3D"color: rgb(0, 0, 0); font-size: 18.6667px; font=
-family: times new roman,new york,times,serif; background-color: transparen=
t; font-style: normal;">www.N91CZ.net<br></div></div></body></html>
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