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.

The issue of HF antenna installation on an aircraft can be generalized with 2 considerations:

• Type of aircraft
• Location of antenna coupler

Since there are numerous types of aircraft with varying installation requirements, there are several HF antenna configurations. Whatever the case may be, the antenna is a major factor for maximum performance of the HF system.

More or less, HF antenna configurations fall into four categories:

“V” and long wire configuration

The “V” and long wire antenna configuration is the optimal HF antenna configuration. It provides consistent performance and efficiency. This configuration should not be used on very high speed fixed wing aircraftand helicopters.

The wing “V” configuration is an effective HF antenna configuration for slow and moderate speed aircraft. This configuration provides an omnidirectional radiation Pattern. It has has the disadvantages of high drag and on low wing aircraft is prone to being walked into.

The inverted “V” antenna is recommended when a wing "V" is not practical and the antenna coupler is mounted in the back of the aircraft. The inverted “V” antenna will produce maximum signal strength off the side of the aircraft and provide good efficiency at most frequencies. The inverted “V” produces a moderate amount of drag.

The long wire antenna is used when the HF coupler is located in the forward part of the aircraft. The long wire provides maximum signal radiation off the sides of the aircraft and exhibit good efficiency even at the lower frequencies. Nulls in signal strength may be experienced off the nose and tail of the aircraft.

Short grounded wire configuration

Short grounded wire antennas are primarily used on higher speed and/or high altitude aircraft. The short wire antenna have minimum drag and do not develop as high of RF voltages as the longer wire antennas. However the efficiency of the short antenna will be lower, especially at the low frequencies.

Shunt configuration

There a generally 2 types of shunt antennas. A towel bar style includes a rod or tube mounted on the airframe usually suited for helicopters.

The other type of shunt antenna is designed by the aircraft manufacturer as a part of the airframe structure on the leading edge of the vertical stabilizer. Leading edge antennas are ideal for Larger, high altitude jet aircraft.

Probe configuration

Probe HF antennas are ideal on aircraft where a long antenna is not suitable. It should be noted that probe antennas provide poor efficiency at lower frequencies as is the case with most short style antennas.

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.