ACK 406/121.5 MHz E-04 ELT FAA TSO

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Complete (New Install)Retrofit Kit
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The E-04 ELT is a direct replacement for the more than 62,000 model E-01 ELT's (by ACK) on the market today. The E-04 fits directly into the current E-01 mounting trays and uses the same remote control panel indicator. The E-04 external antenna will utilize your current antenna mounting and wiring installations.

Note: The installation manual for this item requires the installation of 2 very specific batteries for operation - Duracell part number PX28L or Eveready part number A55 (or equivalent) for installation into the switch assembly and Duracell part number CR2 or equivalent for installation into the audio alert indicator.

Retrofit Kit does not include remote

Warranty: All warranty issues must be handled directly with the manufacturer. These are non-returnable and non-refundable once installed. If any attempts have been made to install this unit it becomes a warranty issue and can only be resolved with the manufacturer directly. Please view the warranty tab for additional information on the manufacturer's warranty.
There is a $250 Recertification fee in addition to the 15% restock fee on all ACK products that have been opened.


  • Accepts GPS position input data from Bendix/King. Garmin, Nema 0183 GPS
  • Antenna is swept back 20 degrees, and features a molded plastic base.
  • 5 watts @ 406MHz for 24 hours, and 100 Mw @ 121.5 MHz for 48 hours.
  • Simple plug in audible alert indicator.
  • Lithium battery pack offers a 5 year battery life, and makes it substantially lighter.


  • 7.75" long
  • 2.85" width
  • 2.85" height
  • 1.6 pounds in weight with battery
  • Remote requires a Duracell PX28L 6 volt lithium battery or an Eveready AS44 battery
  • Audible Alert Indicator requires a Duracell CR2 3 volt lithium battery or equivalent


  • Avionics products manufactured by ACK Technologies, Inc. are warrantied against defects in materials and workmanship for a period of three years from their manufacture date. This warranty is limited exclusively to repair or replacement of the E-04 ELT and associated parts which were manufactured by ACK Technologies, Inc. the defective parts must be returned freight prepaid to our manufacturing facility. This warranty does not include repair or replacement of any part that has been improperly used, installed or physically damaged. This warranty does not cover any damage caused by chemical exposure. Discharge of the ELT lithium battery is not covered by this or any other warranty. Except as provided herein ACK Technologies, Inc. makes no express warranties, and any implemented warranty of merchantability of fitness for a particular purpose is limited in its duration to the duration of the written limited warranties set forth herein. ACK Technologies, Inc. shall not be liable for any direct, indirect, special or consequential damages arising from the use or misuse of this product. Except as provided herein no employee, agent, dealer, or other person is authorized to give any warranties of any nature on behalf of ACK Technologies, Inc. YOU MAY HAVE ADDITIONAL LEGAL RIGHTS WHICH VARY FROM STATE TO STATE

In The Box

New Install Version
  • E-04 121.5/406 MHz ELT
  • E-04.5 Remote with horizontal placard
  • E-04.12.2 Remote vertical placard
  • E-04.8 Whip antenna
  • E- Electrostatic discharger
  • E-04.10.4 Coax cable 60"
  • E-04.7 Audio alert
  • E-04.4 Mounting Tray
  • E-04.4.1 Retaining strap front
  • E-04.4.2 Retaining strap battery case
  • E-04.10.6 Female 4 pin DIN plug
  • E-04.10.5 15 foot remote cable
  • E-04.10.3 Audio alert cable
  • E-04.11.1 Switch cover
  • E-04M Installation/Operation/Manual
Retrofit Kit for ACK E-01
  • 121.5/406 MHz ELT
  • Remote horizontal placard
  • Remote vertical placard
  • Whip Antenna
  • Electrostatic Discharger
  • Audio Alert
  • Female 4 Pin Din Plug
  • Audio alert cable
  • Switch cover
  • Installation / Operation Manual

Note: If customer has ordered retro fit kit in error - they can order p/n: 11-15078 to make it regular ELT kit.


Keith C
September 30, 2020

I dont know how to rate this product since I have not had opportunity to install it yet.

Wade K
September 10, 2020

Fast shipping

Jim K
June 13, 2020

Quick and efficient, we received the ELT in good time and it was installed.

Ted C
May 2, 2020

This ACK EOS-4 was the perfect replacement for my failed Amiri King 450 unit. It came within 1 day and I installed it the next. The instruction manual covered everything including how to register with NOAA. The remote switch fit perfectly were the old one was mounted. I was able to use the existing wiring. The price is right and it has a 5 year battery life. You will have to order online or search for the two batteries required for the Remote Switch and Buzzer alarm. They are not included and cost roughly $10-15 each. The upside is they last eight to ten years. The ACK replacement battery is roughly $180 with tax but lasts 5 years unlike some that are only a 2 year battery and cost almost as much as the unit itself. This is a great product, an amazing safety upgrade to a 406mhz system, easy to install and only needs a log book entry by your A&P I.A. I highly recommend it. P.S. if you are upgrading from an Ameri King unit get the full kit and not the retrofit. It comes with a new mounting bracket, new antenna, new remote switch and all the wiring. It only costs a few dollars more and you will use almost everything. You do have to re drill four mounting holes for the new bracket. It is not the same footprint as your old Ameri King but this is very easy to do. Check out the installation manual on Aircraft Spruce sight or ACK Technologies website. It is all there and very straight forward.

Joe E
April 5, 2020

Very pleased with the ACK E-04 kit. It was very straightforward to replace my ACK E-01 with the E-04, and I was delighted with both the instructions and ease of replacement work. Hatâs off to Aircraft Spruce Canada and ACK.Ray Henault, COURTENAY, BC, Canada

Raymond H
March 29, 2020

Bought this to replace my dead Ameri-King ELT. Need to purchase two batteries, one for the remote and one for the audio alert. About $20 at Batteries Plus and if you go with the lithium variety they dont need to be replaced for 10 years. There are published instructions for retrofitting from the Ameri-King, and it allows you to use the existing remote cable, greatly simplifying the installation. You need to purchase a male-male cable adapter if you go that route, only a couple dollars and included in the box if you buy from Spruce. The only challenging part of the installation, at least in my case since its a fabric aircraft, was the antenna installation. Replaced the existing antenna no problems but ACK includes a static suppressor which is about an inch and a half long and installs between the antenna BNC connector and the cable. The added length coupled with the cable made it too long to fit in the trailing edge of the wing root where it was previously. Solved easily with a 90 degree BNC adapter but be aware. Wouldnt be an issue in fuselage installations. Total installation time was about 4 hours in my relatively simple aircraft which included the online registration with NOAA.

Casey M
March 14, 2020

I purchased the ACK E-04 ELT. I went to ACKs web site and was able to download the instructions to swap out the Ameri-King ELT and install the ACK ELT. I also spoke to Tech support on the phone 408-287-8021.

David P
February 6, 2020

I replaced my battery draining Ameri-King AK-541 ELT with the ACK E-04 ELT and I am happy with the results. The ACK installation guide allowed me to use the existing remote wiring to connect the new ACK panel Remote and Audio Alert when I purchased P/N 11-14707, modular coupler for $4.95. The ACK Remote fit into the same panel hole for the AK-541 Remote, when the screw holes were elongated using a small round file and a vacuum cleaner at the Same Time dont want any metal filings getting into my radios, etc. My I. A. helped and signed off on the installation. The ACK 3 month self test is easy in the cockpit, just push the test button with the radio on 121.5. It is all spelled out in the ACK Installation and Operation manual.

David P
February 3, 2020


January 9, 2020


Q: What is the difference between the USA and international version?

If you have a USA registered aircraft you will need a USA version (programmed for the USA). If you have an aircraft registered outside the USA you will need the international version in which we will need to know the country of registration so we can specifically program. You can fly any where in the world the key is programming to the country of aircraft registration.

Q: What is the difference between complete (new install) and retrofit kit?

If you have an ACK E-01 that you are replacing you can save some money and buy the retrofit kit as you already have parts installed that the E-04 will use. If you do not have an E-01 then you will need to buy the complete kit which will be a new installation.

Q: Does the ACK E-04 ELT transmit your GPS coordinates as well as 406?

By it self, no you will have to connect the E-04 to an external GPS to gain this feature. Refer to the manual for how to connect.

Q: How does an AP/AI test the unit at the annual condition inspection for proper function? Are there any special tools/equipment needed to test?

All of this is stated in the E-04 manual but a unit self test and checking lines for any corrosion is about all you need to do. No tools are needed and cost will only be the time to do the self test and check the lines.

Q: I'm interested in the ACK E-04 to replace a Narco 901 ELT, so I need the full installation kit. What else do I need in terms of panel indicators, etc. that are not in the package. Are there other required parts/special wire to connect to my Garmin panel GPS (530W)?

The E-04 is complete 11-06395 (For USA registered aircraft) for a new installation. For GPS connection you will need to refer to section 6 of the manual (on the Document Tab) which tells you what wire you will need based on your installation.

Q: On page 6, immediately above Figure 9, there is the statement connect the ELT RS 232 data and power to the aircraft systems. Is the ELT to be connected to Aircraft Power? I thought their power was independent from the aircraft.

In most cases yes the ELT is independent of aircraft power unless the manual state so and in this case is require if you add GPS information to the ELT.

Q: Does this ELT meet the requirements for the 406 required for Bahamas travel? With a new installation kit, is it approved for installation in the PA28-180?

The Ack 406/121.5 MHz E-04 ELT will meet the future Bahamas 406 Mhz Requirement and is approved for installation in a PA28-180.

Q: What is the battery replacement item for the ACK 406 E-04 ELT?

The replacement battery for the ACK 406 E-04 is part# 11-10012.

Q: What is included for a new installation?

The ACK 406/121.5 MHZ E-04 ELT comes with the ELT, Antenna, Remote Switch, Alert Buzzer and wiring.

Q: Is a whip antenna available for the AKC-406/121?

Yes, the Whip antenna for the ACK 406/121.5 MHZ ELT is P/N 11-10465.