Cannot replace a Mode C transponder
In fact, one could remove all of the components and the interconnecting wiring and provided that the overall configuration remains the same in terms of LRU part numbers, the installation / system remains unchanged.
So if I remove the antenna and replace it with the same part number/mod status, remove the antenna coax and connectors and replace them with the same part numbers/mod status, remove the mounting rack and electrical wiring and replace them with the same part numbers/mod status, and the remove the TX/RX unit and replace it with the same part number/mod status, I have not installed a "replacement ... system", even though I literally replaced the system.
I only install a "replacement system" if I install a system that has different part numbers?
Join Date: May 2004
Location: Granada, Spain
Posts: 218
Likes: 0
Received 0 Likes
on
0 Posts
That would be my interpretation and over the life of the aircraft that could happen...
We had a visiting Falcon 20 with a dual all in one GPS / FMS UNS-1 Nav system... just two major components, the main Display / Computer unit and an active GPS antenna... Owner reported that 15minutes into every flight, the Captains display blanked and remained off until rebooted giving a further 15 minutes of use... Owners had replaced the FMS unit three times; all the wiring checked out OK and the FMS units checked out serviceable on the bench. The problem was diagnosed eventually to the GPS Antenna driving the Captains box... its an active antenna and needs a 15V supply which it derives from the Nav unit; in this instance the antenna had developed an internal short circuit which was loading the 15v rail that also powered the display until its self protection system kicked in ... The repair involved replacing the Antenna...
By the logic described in the original question, in replacing the FMS unit, the owners had changed the installation, by removing and bench checking the same unit we had done so too; similarly in replacing the antenna we had changed the installation.
In reality because like was replaced with like nothing had changed insofar as the installation was concerned... The items carried the same part numbers as the original fit, the serial numbers had changed but that irrelevant.
We had a visiting Falcon 20 with a dual all in one GPS / FMS UNS-1 Nav system... just two major components, the main Display / Computer unit and an active GPS antenna... Owner reported that 15minutes into every flight, the Captains display blanked and remained off until rebooted giving a further 15 minutes of use... Owners had replaced the FMS unit three times; all the wiring checked out OK and the FMS units checked out serviceable on the bench. The problem was diagnosed eventually to the GPS Antenna driving the Captains box... its an active antenna and needs a 15V supply which it derives from the Nav unit; in this instance the antenna had developed an internal short circuit which was loading the 15v rail that also powered the display until its self protection system kicked in ... The repair involved replacing the Antenna...
By the logic described in the original question, in replacing the FMS unit, the owners had changed the installation, by removing and bench checking the same unit we had done so too; similarly in replacing the antenna we had changed the installation.
In reality because like was replaced with like nothing had changed insofar as the installation was concerned... The items carried the same part numbers as the original fit, the serial numbers had changed but that irrelevant.
Just so I have it clear in the context of a discussion about the requirement to fit Mode S....
Bob owns a Cessna 172R fitted with a Brand X transponder system without Mode S. Bob can replace his transponder system with the same Brand X part no. system without Mode S and that is legal and safe.
Jeff also owns a Cessna 172R, but it is fitted with Brand P transponder system without Mode S. Jeff can replace his transponder system with the same Brand P part no. system without Mode S and that is legal and safe.
But if Jeff's transponder system goes kaput and Bob happens to be parting out his aircraft, it's not legal or safe to install Bob's Brand X system in Jeff's aircraft to replace the Brand P system?
Bob owns a Cessna 172R fitted with a Brand X transponder system without Mode S. Bob can replace his transponder system with the same Brand X part no. system without Mode S and that is legal and safe.
Jeff also owns a Cessna 172R, but it is fitted with Brand P transponder system without Mode S. Jeff can replace his transponder system with the same Brand P part no. system without Mode S and that is legal and safe.
But if Jeff's transponder system goes kaput and Bob happens to be parting out his aircraft, it's not legal or safe to install Bob's Brand X system in Jeff's aircraft to replace the Brand P system?
Join Date: Nov 2015
Location: Dog House
Age: 49
Posts: 779
Likes: 0
Received 0 Likes
on
0 Posts
modified by having its transponder installation replaced on or after 6 February 2014;
Avionics systems and installations follow the same rules and regulations as engine and airframe.
By removing a TSIO 540 J2B and fitting an exchange factory overhauled TSIO 540 J2B. Has the installation been modified?
No modification has taken place (even if part numbers of cylinders are different) it is still a J2B.
Modification. A modification to an aeronautical product means a
change to the design of that product which is not a repair.
Avionics systems and installations follow the same rules and regulations as engine and airframe.
By removing a TSIO 540 J2B and fitting an exchange factory overhauled TSIO 540 J2B. Has the installation been modified?
No modification has taken place (even if part numbers of cylinders are different) it is still a J2B.
Modification. A modification to an aeronautical product means a
change to the design of that product which is not a repair.
And the answer to my question is ...
Join Date: May 2004
Location: Granada, Spain
Posts: 218
Likes: 0
Received 0 Likes
on
0 Posts
@Lead Balloon... But if Jeff's transponder system goes kaput and Bob happens to be parting out his aircraft, it's not legal or safe to install Bob's Brand X system in Jeff's aircraft to replace the Brand P system?
Join Date: Nov 2015
Location: Dog House
Age: 49
Posts: 779
Likes: 0
Received 0 Likes
on
0 Posts
The OP could give the repaired unit to his LAME to refit, get the LAME to make a Log Book entry "Transponder P/N xx S/N removed for repair and refitted".
Get LAME to enter on Maintenance Release "AD/RAD/47 A4 due" then get local Avionics shop to carry out a RAD 47 and sign off on MR.
Return to Service Requirements
For VFR aircraft, the airframe and engine privileges allows for an airframe LAME to certify for the replacement of removable items of radio equipment.
Note: Be aware that a functional test to establish the integrity of the code lines will be required when replacing a Mode C equipped transponder utilising the altitude data from a Gillham source. As special test equipment is required this task will require the certification of an appropriately trained and rated LAME.
Get LAME to enter on Maintenance Release "AD/RAD/47 A4 due" then get local Avionics shop to carry out a RAD 47 and sign off on MR.
Return to Service Requirements
For VFR aircraft, the airframe and engine privileges allows for an airframe LAME to certify for the replacement of removable items of radio equipment.
Note: Be aware that a functional test to establish the integrity of the code lines will be required when replacing a Mode C equipped transponder utilising the altitude data from a Gillham source. As special test equipment is required this task will require the certification of an appropriately trained and rated LAME.
Bob owns a Cessna 172R fitted with a Brand X transponder system without Mode S. Bob can replace his transponder system with the same Brand X part no. system without Mode S and that is legal and safe.
Jeff also owns a Cessna 172R, but it is fitted with Brand P transponder system without Mode S. Jeff can replace his transponder system with the same Brand P part no. system without Mode S and that is legal and safe.
But if Jeff's transponder system goes kaput and Bob happens to be parting out his aircraft, it's not legal or safe to install Bob's Brand X system in Jeff's aircraft to replace the Brand P system?
Jeff also owns a Cessna 172R, but it is fitted with Brand P transponder system without Mode S. Jeff can replace his transponder system with the same Brand P part no. system without Mode S and that is legal and safe.
But if Jeff's transponder system goes kaput and Bob happens to be parting out his aircraft, it's not legal or safe to install Bob's Brand X system in Jeff's aircraft to replace the Brand P system?
That is correct Lead. That is a modification not a repair.
Join Date: Nov 2015
Location: Dog House
Age: 49
Posts: 779
Likes: 0
Received 0 Likes
on
0 Posts
From memory several blind encoder brands are interchangeable.
A-30 blind encoder.
mod 1,2,3,4 & 5 different wiring mod 6,7,8 &9 same plug.
Same regulatory genius will apply. So a $100 part (or swapping 2 wires over) could ruin your day if they no longer make or repair your breed.
A-30 blind encoder.
mod 1,2,3,4 & 5 different wiring mod 6,7,8 &9 same plug.
Same regulatory genius will apply. So a $100 part (or swapping 2 wires over) could ruin your day if they no longer make or repair your breed.
Last edited by Band a Lot; 18th Aug 2016 at 03:23.
OMG, I'm starting to think like CASA - negative affirmations:
So if you improve the efficiency of your existing product via a software upgrade which involves no physical change to the product, what have you done?
Modification. A modification to an aeronautical product means a
change to the design of that product which is not a repair.
change to the design of that product which is not a repair.
Join Date: Nov 2015
Location: Dog House
Age: 49
Posts: 779
Likes: 0
Received 0 Likes
on
0 Posts
Nothing actually other than maintenance.
It is still (if by manufacturer) part of original Type Data Certificate or approval approved by a relevant authority.
eg Improved and different P/N cylinders on the TSIO 540 J2B engine for about 15 times in last 50 years.
It is still (if by manufacturer) part of original Type Data Certificate or approval approved by a relevant authority.
eg Improved and different P/N cylinders on the TSIO 540 J2B engine for about 15 times in last 50 years.
Modification vs repair
Band a lot has hit the nail on the head. As for as CASA are concerned "the design" for a product is what is included in the TCDS, ATSO standard or TSO standard. If this does not change with the software update or part number change then the "design" has not been modified.
As for the Bobs old transponder cannot be fitted to Joe's plane argument, I think it is reasonable to require upgrade to the latest standard when a new complete system is being installed. The installation of a different system will require engineering approval or an STC as well as Avionics LAME regardless if it is old or new standard. As a result the price difference between fitting a complete mode C and a complete mode S will be minimal.
So repair your mode C until a lack of parts makes a mode S upgrade the cheaper option.
As for the Bobs old transponder cannot be fitted to Joe's plane argument, I think it is reasonable to require upgrade to the latest standard when a new complete system is being installed. The installation of a different system will require engineering approval or an STC as well as Avionics LAME regardless if it is old or new standard. As a result the price difference between fitting a complete mode C and a complete mode S will be minimal.
So repair your mode C until a lack of parts makes a mode S upgrade the cheaper option.
So it's legal and safe to have two 172Rs, one with a Brand X transponder system and the other with a Brand P transponder system, neither with Mode S.
But it's not legal and safe to swap those transponder systems and end up with two 172Rs, one with a Brand X transponder system and the other with a Brand P transponder system, neither with Mode S.
I guess it shows that one man's "reasonable" can be another man's "mule-stupid".
But it's not legal and safe to swap those transponder systems and end up with two 172Rs, one with a Brand X transponder system and the other with a Brand P transponder system, neither with Mode S.
I guess it shows that one man's "reasonable" can be another man's "mule-stupid".
Join Date: Jan 1999
Location: Abeam Alice Springs
Posts: 1,109
Likes: 0
Received 0 Likes
on
0 Posts
This might answer the original question and some of the posts since?
If fitting a new transponder Post 6 February 14 a mode S transponder is required unless the aircraft is restricted to operations Below A100 in Class G and Class D. In such areas a mode C transponder is acceptable.
Or not.
It's certainly irrelevant to the question I asked.
It's certainly irrelevant to the question I asked.
