Bringing Cardinal Owners Together
for safety, savings and fun
Welcome Guest
Join or Log In
  Home |  Prepurchase |  Ops |  Digest |  Members |  Mods |  Tech |  Data
Tech Index

Alphabetic Index

A
ADs
Aileron Trim Tab
Aileron Bellcrank
Air Box Rebuild
Air Box Repair
Air Duct/Spar
Air filter Gasket
Air filter mods
Alternate Parts sources
Alternate Air Door
Alternator Bracket
Alternator Circuit Breaker
Alt Circuit Breaker kit
Alternator Debug
Alternator Fix??
Alternator noise
Alternator, Standby
Ammeter blip
Amsafe Install
Antenna Mount
Annual Inspection
Autopilot
  300AP transistors
  300AP hints
  Bellcrank
Avionics Air Scoop

B
Back seat removal
Baffle Mods
Baffle Rebuild
'68 Baffle Mods
Baggage latch spring
Bellcrank, Aileron
Belly Cleaning
Bike Rack
Brackett Air Filter
Brake hose FG
Brake master FG
Brake hose RG
'Braly Mod'
BAS seat belt
Boroscopes
Brake Swivel (RG)
Bulkhead repair ('68)
Bungee (Steering)
Bus Bar repair

C
Camera Windows
Carb Data
Carbon Monoxide
Case mods
CAT tubing replace
Charging Debug
Chart desk/table
Compass leaks
Console Repair
Console: add-on
Cooling Cylinders
Cooling in Climb
Cover review
Cowl
  '71 mods
  Baffle mods
  Bumper
  Bumper 2
  Camloc Fasteners
  Camloc Issues
  Camloc Evolution
  Chafing Mods
  Eyelets
  Flap cable replace
  Flap exit ramp
  Flap fences
  Flap bumpers
  Flap Exit
  Flap Effectiveness
  Grommets
  Rubs on Spinner
  Southco fasteners
  Screws
  Custom Inlets
  Inlet Fences
Cylinder Cooling
Cylinder cooling details
Cylinder "doghouse"
Cylinder inspection

D
Defroster fan
D Engine swap (FG)
D Engine swap (RG)
Display repair
Door
  Fuse damage
  Handles
  Handle option
  Hinge reinforcement
  Hinge repairs
  Latch lube
  Locks
  Pin alignment
  Seals (updated)
  Seal source
  Seal replacement
  Spring replacement
  Tightening
Doubler repairs
Drilled yoke
Dual cone speaker
Dukes Fuel Pump

E
Elevator: see Stabilator
Electrical Noise
Elevator Trim Rod clearance
Engine Cables
Engine Gages
Engine mount
Engine swap (D)
Exhaust fairings

F
FG Strut Rebuild
FG Strut Rebuild 2
Firewall Forward mod
FG Jacking
FG Fuel Flow
Flap Motor source
Flap Noise
Flaps Slow
Flap adjustment
Flap Adjust Problems
Flap Follower cable
Flap Follower cable Options
Flood light
Fuel Caps
  Flush Cap rebuild
  Monarch thoughts
  Monarch Install story
  Replacement Options
  Types
Fuel
  Aux Tanks
  Dipstick
  Drain valve
  Dukes Pump(RG)
  Dukes Pump Option
  Feeding unevenly
  Flow FG
  Gage info
  Header Tank leak
  Hose replacement
  Indicator repair
  Quick Drain (FG)
  Shutoff issues
  Shutoff rebuild (FG)
  Tip Vent
  Selector Valve rebuild
  FG Valve rebuild
  FG Valve rebuild 2
  Vent leak (crossover)
  Weldon Fuel Pump (RG)
'68 Fuse Repair

G
Gap Seals
Gages
Gear Indicator lights
Gear Light Secrets
Gear Magnets
Gear Mirror
Gear pump brushes
Gear pump Diagnosis
Gear Pump Light
Gear pump rebuild
Gear wobble (FG)
Governer control lube
Governer plate
Gov plate: One Mech's View
Governer Surge
Grab Handle Clip
Green Goo

H
Handicapped passengers
Handle Clip
Headrests
Headlights
Headlight Replacement
Heater improvements
  Exhaust fan
  Bulkhead seal
  Aux heat tube
  Tailcone mods (RG)
  Flow Improvement
  Underseat fans
Heavy Wing
Hoisting
Horton STOL
Hose Standoffs
HP Plus Mod
Hydraulic Hoses (RG)

I
Ignition: Lasar
Injection system
Injector Clamps
Intake Manifold Seal
Intercom noise
Interior parts
Interior Rework

J
Jacking the FG
Jacking the RG
Jack options
Jack buying
Jack building
Jacks: my design

K
King display repair
Kinzie presentation
Kinzie install


L
Landing Gear (FG)
Landing Lights
Landing Light Replacement
Lasar Ignition
LED Lights
 Wing tips
 Gear indicators
Light (flood)
Lighting troubleshoot

M
Magnets (gear)
Magneto points
Manifold Pressure gauge
Manuals
Mixture cable (Cablecraft)
Mixture Cable Attach
Monarch Fuel Cap Install
Muffler
  Bracket Removal
  Clamp (RG)
  Cracks

N
Nav Light Indicator
Nose Gear
  NG arm pad
  Drag link cracks (RG)
  Door Hinge (RG)
  Door wear
  NG Door Grommets
  Door Grommet option
  Door Bumper
  Shimmy
  Strut rebuild (RG)
  Strut Rebuild (FG)
  Swinging
  Door Triming
  Uplock Roller (RG)
  Tow Limits

O
Oil Canister issues
Oil Cooler Baffle (RG)
Oil Cooler Info
Oil Cooler gap (RG)
Oil Cooler upgrade (RG)
Oil Draining tricks
Oil Filter (D) Adapter
Oil Filter Cutting
Oil leaks
Oil line: prop
Oil Paths
Oil Pump
Oil Separator
Omni antenna
Overhaul
Over Voltage switch
O/V switch wiring
Owner Maintenance

P
Panel forming
Panel Project
Panel Tilt
Paint
  Colin's Paint Story
  Hints and Tips from Guy
  RG Colors
  FG Colors
  Painting templates
Pitot-Static Troubleshooting
Placards
Preflight Inspection
Prop control lube
Prop oil line
Prop oil line fitting
Prop Surge
Prop Torque
PTT options
PTT in Yoke
Pump rebuild: gear

Q

R
Radio noises
Rain leaks
Retractable Gear (RG)
  Alternate Air Door
  Ammeter blip
  Brake Swivel
  Gear Lights
  Gear Magnets
  Gear Mirror
  Gear pump Diagnosis
  History
  Hoisting
  Jacking
  Lights
  Main Gear Pin
  Main Rod End
  Main Rod End Sources
  Manifold
  MG up-bumper
  MG Saddle Replace
  MG Saddle Repair
  MG actuator bracket
  NG Door wear
  NG drag link
  NG Hoses
  NG Swinging
  NG Switch wire
  NG arm pad
  NG Door Trim
  Pressure Switch
  Pump brushes
  Pump bypass leak
  '71-3 Pump Manifold
  Reed switch
  Reed switch rebuild
  Rod End
  Rod End sources
  Schematics
Speaker (gear warn)
  Squat switch wire
  Throttle switch arm
  Throttle switch example
  Troubleshoot
  Uplock Roller (RG)
  Warning cam
  Warning horn
Rear seat removal
Rigging
Rosen Sun visors
Royalite Replacements
Rudder trim

S
SCAT tubing installation
Screw Removal
Seats, rear
Seat belts for 2
Seat rails
Serial numbers
Service Bulletins
Shimmy dampener
  RG rebuild
  FG issues
  Solutions
  More FG
  FG solution
Shimmy
Shoulder harness
Sound Proofing
Sound Insulation
Southco fasteners
Spar Cap inspection
Spar Cap cracks (177)
Spar Cap cracks (210)
Spar Carrythrough
Spar Pins
Spar Repair
Spare repair avoidance
Spar Replacement
Spar Bracket Crack
Spar Servicability
Speaker: Dual Cone
Speed mods
Spinner Issues
  '68 Spinner
  Paul's Spinner
  Chuck's Spinner
  Rubs on Cowl
STD Temp
Steering Bungee
Squat Switch
Springs
  Wing Tiedown Ring
  Door holdopen
Squat Switch
Stabilator
  Balance
  Bracket cracks
  Bracket inspection
  Bracket rework
  Bracket fasteners
  Bushings
  Creaking noises
  More Brackets
  Trim Rod clearance
  Trimming
  Wobble
  '68 Stab attach
Stall switch
Standby Alternator
Standoffs
Static System Troubleshooting
S-Tec autopilot
STCs
Step removal
STOL kit
Strobes, adding
Strut rebuild (RG)
Strut Rebuild (FG)

T
Tach cable
Tailcone Bird cover
Throttle cable
Throttle cam
Tiedown Ring spring
Tilt in Panel
Turbocharging
  Air Foil Bearings
   Primer
  Checklist
  Heat Exchanger
  Install Info
  FG Virtual tour
  RG Virtual tour
  Paul's pics
  Parts List
  Performance
  Power Setting
  System Overview
  Operations Manual
  Vacuum Seal
  Vince's pics
  Keith's pics
Type Cert Data
U
Uplock Actuator (RG)
Uneven Fuel Feed

V
Vacuum Seal
Vent Hoses
Vent window crank
 Vent Example
Vernatherm Theory
Vernatherm Fix
Voltage Regulator
Voltage (low)
Vortex Generators
VG Installation

W
Water leaks
Wheelchairs
Wheel hub cracks
Whisker antenna
Windshield leaks
Window replacement
Window crank, vent
Wing Pins
Wing removal
Wing Rigging
Wing smoothing
Wing Tiedown Ring
Wing tip mods
Wing Vent hoses
Wire Standoffs

X

Y
Yoke Drilling

Z
  

Spar Carrythrough Corrosion

and Air Ducting


Jan Hovat, our reader from Norway, first brought the issue of spar carrythrough corrosion to our attention. We were able to get his problem resolved, but since then we have heard of several airplanes that required replacement of this part, and many others that were close to having a problem.

Click here to read Tom Connor's discussionof how he redid his air ducts to avoid such issues in the future.

If it's too late for you, see Peter Staeuble's spar replacement story.

This issue should be high on the list of details that should be looked into at your next annual. If you find corrosion on your spar carrythrough, you should review this page for information on the specifications for servicability.

Here is Jan's story:

From: "Jan Hovet" (hovetco@online.no)

Subject: C177 Severe corrosion detected in wing spar

My mechanic found some severe (my own description; not technical) corrosion on the wing carrythrough spar today, by the holes where the air vent hoses go. Our guess is that the thin steel wires in this hose has been rubbing against the aluminium. It is so bad that the aircraft is no longer considered airworthy. Stricken by panic, I suddenly foresee that the whole spar must be replaced, and that the cost will be too high for the aircraft.

Does anyone know approximately what cost I should typically be looking at, or what can be done in such a situation?

What Jan had found was that the spar had substantial corrosion in the area near the hole where the air vent hoses passed through it. The hoses on the right side of the airplane can be seen in the above picture.

Then came a later note from Jan..

From: "Jan Hovet"
Subject: Wing carrythrough spar corrosion

About a week ago, I reported severe corrosion on my wing carrythrough spar. Cessna has authorized scraping away the corrosion on the worst places, but my mechanic feels that there are too many of them, and that only changing the spar will really fix the problem in the long run. There is also some starting corrosion the side of the spar, where you cannot scrape it away without taking off the wing. And according to Cessna, these spars are no longer available, although previously made to order. Does anybody know where I could obtain a new or overhauled (or "experienced" as they call "used") unit?

As the second picture shows, there are more tubes on the left side of the airplane that also pass through the spar.

The problem with these tubes is that they are the lowest grade of tubing of this type, called Cat tubing. They are not impervious to moisture, so when the rain comes in it tends to soak the hoses and create a point of corrosion between the steel spiral wire and the aluminum spar carrythrough structure.

The picture below shows a place where the Cat tubing is actually tied up to the spar, causing a potential wear and corrosion point. In this installation there is a pad between the parts, but other owners have reported no such pad and in some cases substantial corrosion.

More from Jan as his saga continues:


From: "Jan Hovet"
Subject: Got a new spar!
As you know, I have a corroded carry-through wing spar that needs replacement soon, and I am happy to report that I now have one, which came off 88WC. I have not been able to inspect it yet, but the immediate impression is that it is a lot better than my existing one. I'll have to put it through some non-destructive testing. And I would never have found one without the great help I got from Keith Peterson, who has invested considerable time and effort in finding this one for me. Thank you so much, Keith, and if you do come over here, Keith, we'll go flying in the mountains together!

The solution that most Cardinal Flyers have gone to was the replacement of the Cat tubing with Scat tubing, a version with a much better resistance to moisture. With some improvements in the attachment methods and better padding between aluminum and tubing they felt confident that their spar would not suffer any problems.

Here's a followup from another reader who checked his recently:


From: Rick Wayne (fewayne@facstaff.wisc.edu)
Subject: redbird's annual
Finished up my part of our 1975 177B's annual last night, I wound up taking four days off work to do it but it was worth it, as usual. I took the list's recommendation to drop the headliner in order to get a good, unobstructed look at the spar carrythrough and such, and was very glad that I had. Turned out there was a tiny bit of surface corrosion on the spar CT; not enough to worry anyone, but definitely enough to clean off and treat. Probably saved us BIG bucks a few years down the line.

For information on replacement of the duct tubing, so as to avoid this problem, check out this page.


These pages are a collection of the ideas and impressions of the Cardinal pilots who frequent this site. This information is anecdotal, informal and may not be completely accurate. The Cardinal Flyers are not certified mechanics and do not guarantee the accuracy of the contents of these pages. Please research and confirm anything that is referenced on these pages with the experts appropriate to your situation.

As always, the Cessna maintenance, operations and flight manuals, and the advice of a certified mechanic and flight instructor, should be your primary sources of information regarding safe maintenance and operation of your aircraft.



Copyright Cardinal Flyers Online LLC 1997-2017