Yes, Service Bulletin 8 must be performed on the TCR-220 and Service Bulletin A on the CTL-220 to add Lower Sideband (LSB) to the HF-220 system.

Southeast Aerospace exchanges are based on the return of an undamaged, economically repairable core unit with identical part number as the unit shipped to the customer. An "economically repairable" core is defined as one where the cost to repair/overhaul (or Repair Cap) does not exceed 80% of the original SV/OH exchange price billed. Should the Repair Cap exceed 80%, the customer will be billed the additional amount. In the event this amount exceeds the Outright Price for the unit, the customer would only be billed the difference between the Outright Price and SV/OH Exchange Price with the core returned as-is to the customer.

Here is an example of such a transaction:

$1000 Exchange Price charged to customer
$1000 x .8 = $800 Maximum Allowable core repair charge or Repair Cap

$2000 Cost to repair core unit
- $800 Less Core repair cap
---------
$1200 Additional billing amount.

2200.00 Total Cost of transaction

Please Note:
SEA offers exchange on new items as well. However, repair cap as indicated above is still based on SV/OH exchange price.

In most cases, a Supplemental Type Certificate is not required for the installation of an HF system. Major changes or alterations to an aircraft may include those which affect weight, balance, structural aspects, reliability, operational characteristics, airworthiness characteristics, etc. Some major alterations can be performed using the FAA Form 337 with approved data. This approved data can be in the form of engineering data with a FAA designee approval (i.e. DER, DAR). The DER or DAR then issues an FAA Form 8110 which is considered approved data adequate to proceed with the installation.

HF installations in the USA are installed and approved in the method detailed above. STCs are not required for almost all HF installations since the change to the existing aircraft Type Certificate (TC) is not so intensive as to require one.