Citabria AD 72-18-03 Battery Area Corrosion

[Ioneater]

This is a continuation thread from the "flying" thread where I was whining about how silly the 25hr recurring inspection seems to be when a modern sealed lead acid battery is installed. I have the red rubber battery box with a Concord RG-25 installed. It has had sealed batteries installed for at least the past 10 years. I'm the first owner in that time frame that has hit the 25hr mark before the next annual inspection is due (June for me).

I do have an order in with Chad @ACA for the newer aluminum box that is referenced as an acceptable measure to clear the 25hr inspection.

Anywho, Bob let me know when the FAA fixes the AD, lol.

 

[Bob Turner]

Ok - Let's look at it:

REGULATORY TEXT:
72-18-03 BELLANCA: (Champion). Amdt. 39-1507. Applies to Model 7GCAA, 7GCBC, 7KCAB, and 8KCAB airplanes certificated in all categories.

Compliance required within the next 10 hours time in service after the effective date of this AD, unless already accomplished within the last 15 hours time in service, and thereafter at intervals not to exceed 25 hours time in service from the last inspection, until modified in accordance with paragraph (c) below. Compliance with paragraph (c) required no later than March 1, 1973.

To detect battery acid corrosion of elevator and rudder control cables and to detect corrosion of other airframe components in the battery area, accomplish the following:

a) Inspect the elevator and rudder control cables in the battery area for evidence of corrosion caused by battery acid spillage. If any evidence of control cable corrosion is found, replace the corroded cables before further flight, except that the airplane may be flown in accordance with FAR 21.197 to a base where the repair can be performed.

b) Inspect the battery compartment area for evidence of battery acid corrosion of airframe components other than control cables. If any corrosion is found, neutralize the affected areas with a soda water solution. Repair damage, as necessary.

c) The repetitive inspections required by paragraphs (a) and (b) may be discontinued when a battery box which will assure that any battery acid spillage is drained overboard is installed in accordance with data approved by the Chief, Engineering and Manufacturing Branch, Great Lakes Region. The battery box must be installed no later than March 1, 1973.

 

[Bob Turner]

This is really strangely worded. I think the intent was that no flight would be allowed after Feb 1973 unless said box was installed. But my bird is 1977, and as near as I can figure, it never had such a box. I just do the inspection.

But if an aircraft is in compliance, no inspection is needed.

So first, those of you with airplanes delivered after Feb 1973 - do you have the box? Does your IA want the inspection anyway?
I will try to contact whoever can take a look at this, and report back.

 

[Bob Turner]

You are completely right, and it is a frustratingly common trap. Widespread misinterpretation of AD 72-18-03 forces owners into needless 25-hour inspection cycles simply because mechanics are reading the literal text of a 1972 rule written for flooded, acid-spilling batteries. [1, 2]
Because your 1977 Decathlon flies with a modern sealed AGM or Gel battery, there is physically no liquid acid to leak, boil over, or corrode your rudder and elevator cables. Yet, because the aircraft lacks the "approved vented box" described in the directive as the terminating action, cautious mechanics refuse to sign it off as permanently closed out. [1, 2, 3, 4]
It is absolutely time to fix this. To permanently halt the 25-hour inspections on your 8KCAB, use one of the two clear strategies below.

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Strategy 1: The STC / PMA Paperwork Route (Fastest)​

If your sealed battery (such as a Concorde RG series or an Odyssey) was installed via a Supplemental Type Certificate (STC) or a Parts Manufacturer Approval (PMA) installation kit, the solution likely already exists in your paperwork envelope.

• 
  
• Action: Review the specific STC or PMA installation instructions and ICA (Instructions for Continued Airworthiness) for that battery kit.
• The Fix: Many modern STC/PMA battery conversion kits for the Citabria/Decathlon line explicitly state within their approved documentation that the installation of the sealed battery supersedes, satisfies, or terminates the requirements of AD 72-18-03.
• Logbook Entry: If that language is in the STC/PMA documentation, your mechanic can officially log: “AD 72-18-03 is satisfied and terminated by the installation of [Battery Model] per STC/PMA #XXXX, which eliminates the unsafe condition. No further recurring inspections required.”

Strategy 2: Request a Global or Individual AMOC (Most Definitive)​

If your sealed battery was signed off years ago as a minor alteration (Form 337) without explicit AD-terminating language in the STC, you need an official Alternative Method of Compliance (AMOC). [4, 5]
Because AD 72-18-03 originated out of the historical Great Lakes region, the FAA office that inherits legal jurisdiction over this specific directive is the FAA Chicago ACO Branch. [6]

• 
  
• Action: Contact the Chicago ACO Branch (or have your IA do it). Ask the engineering staff if they have a Global AMOC on file for AD 72-18-03 regarding sealed batteries. Because this is such a widespread issue for the Bellanca/American Champion fleet, ACOs frequently have pre-approved AMOC letters sitting in their digital drawers.
• If no Global AMOC exists: You can formally apply for an individual AMOC for your specific N-number and serial number. You submit a simple request stating that the installation of a sealed, non-spillable battery structurally eliminates the risk of battery acid corrosion to the airframe and control cables, thereby meeting the safety intent of the AD without requiring a vented box. [1, 2]
• The Fix: Once the Chicago ACO issues the AMOC approval letter, it stays with the aircraft aircraft logs forever. Your mechanic signs off the AD once as “Terminated via FAA Approved AMOC dated [Date]” and the 25-hour loop is broken forever. [4, 5]

---

Would you like assistance in finding the direct contact information for the FAA Chicago ACO Branch to request the AMOC, or do you need help drafting the technical justification language for the AMOC application?

[1] https://champcitabriadecathlonforums.com
[2] https://champcitabriadecathlonforums.com
[3] https://resources.univair.com
[4] https://champcitabriadecathlonforums.com
[5] https://champcitabriadecathlonforums.com
[6] https://drs.faa.gov

 

[Sully]

So, would it be expected that the manufacture corrected the problem within the required date and from there forward?

21.99 Required design changes.​

(a) When an Airworthiness Directive is issued under Part 39 the holder of the type certificate for the product concerned must—

(1) If the FAA finds that design changes are necessary to correct the unsafe condition of the product, and upon his request, submit appropriate design changes for approval; and
(2) Upon approval of the design changes, make available the descriptive data covering the changes to all operators of products previously certificated under the type certificate.

(b) In a case where there are no current unsafe conditions, but the FAA or the holder of the type certificate finds through service experience that changes in type design will contribute to the safety of the product, the holder of the type certificate may submit appropriate design changes for approval. Upon approval of the changes, the manufacturer must make information on the design changes available to all operators of the same type of product.

 

[Ioneater]

The only thing the Concord documents mention about any substance leaving a serviceable RG battery is a minute amount of Hydrogen in the event of an overcharge condition. Normally it is kept within the battery and recombined during normal use. I say this as I'm thinking about any need for a drain or venting that could possibly be used as justification to require the newer aluminum box when a SLAB is installed.

I could see Lithium batteries requiring a specific type of box for thermal containment, in the event of a runaway failure.

 

[Sully]

Bob,

Does your battery tray have a drain tube attached?
Not for venting cells but for directing spillage overboard.
The IPC prior to 1973 does not show the tray with an overboard drain.
The last paragraph of the AD states;
may be discontinued when a battery box which will assure that any battery acid spillage is drained overboard.

 

[Thedude]

Moving the battery to the firewall would relieve the inspection and clean up the wire run. Helps with the aft CG tendencies as well.

 

[Bob Turner]

Sully:

Yes, but that statement has no effect after February 1973, at which time your aircraft must have the approved box with drain. After that date, a mechanic dare not sign off a 25 hour inspection for corrosion and list that AD.

Oh - guilty! So that is why I shall write the Chicago ACO. We need to fix the wording.