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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.
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Easy install. Good instructions.

Gary G
October 18, 2019

Ordered a ACK E04 with other parts on a Tue, received it the next day. Way to go Aircraft Spruce.

Charles L
October 9, 2019

Having researched all the ELTâs, this one seemed the best bang for the buck. Saw a few negative reviews but they seemed to be the exception. Just started installing on my nearly complete Zenith 601XL. Install was pretty simple. All the complaints about the 2 batteries needed for this unit are ridiculous. Picked them up at Ace Hardware for around $10 - No big deal! Called Ack with one install question and got my answer right away. And the swept antenna looks much better than the competitors stubby wire one. Received quickly and in good shape - thanks Aircraft Spruce.

Mark S
October 4, 2019

No coupler to attach the antenna to the ELT came in the package.

Stephen R
August 16, 2019

The ACK 406/121.5 MHz E-04 ELT is well designed and lightweight, but the installation package is incomplete. ACK leaves it to the installer to source two different, hard to find speciality lithium batteries costing about $10 each. These specialty batteries are required to power the remote switch (6v) and buzzer (3v). Including these batteries would be easy at very little additional cost to ACK. I hope Aircraft Spruce will insist ACK include these batteries, making the installation kit complete. I would have saved a lot of time and money if these two batteries had been included. It is also my hope Aircraft Spruce will include the option of ordering these two batteries when customers order ELT replacement batteries Part # 11-10012. BUYER BEWARE

Richard R
June 17, 2019

Tony G
September 26, 2018

Yes if you get water in the remote or audio alert it can set off the ELT electronics do not like water much. The ELT itself is waterproof to 60 feet of water for 48 hours. With over 25,000 units now in service the problems we do see are almost always traced back to electrical equipment or antennas in close proximity to the ELT or control wiring. Make sure you follow the guidelines in the manual regarding antenna separation and cable routing. Water getting into the remote or audio alert in an area subject to water intrusion such as below side windows, leaky windshields, the wing root of Cubs etc will cause activation if the equipment canât be move wrapping it with Saran Wrap will protect it. If your having problems always start with our trouble shooting guide available on our web site. http://www.ackavionics.com/wp-content/uploads/2018/03/Trouble-shooting-E-04.pdf

Mike A
September 4, 2018

Do not recommend at all. Has been nothing but problems since I installed it 3 years ago. Overly sensitive g-switch would set the ELT off simply loading bags into the airplane (3 feet ahead and a bulkhead separating the baggage area from the ELT mount). Sent in for repair, they claimed nothing was wrong. Moisture from flying in rain/condensation shorts out the ELT even if trace amounts of moisture get into the speaker. Their fix? Put it in a ziplock bag. The final straw was this years re certification it failed the power output test (3 years old only). Contact ACK, no response. Avoid this product and company.

Craig R
July 1, 2018

The ACK E-4 406 ELT is lighter than my old AmeriKing unit. A small bracket modification was needed, but otherwise it installed very easily in my 1960 C-182. The customer service person at Aircraft Spruce recommended I order the $4 adaptor, which arrived in the same box, and completed the interface into my panel wiring. I recommend this unit.

April 19, 2018

Over all an easy install. Wired it up to my Avmap Ultra for GPS input. Good bang for the buck. Things that Im not happy with, why not include the little batterys that are needed to make it all work?? Not a real big deal $10 on Ebay got me a set, but for $500 you think they would be included. On the other hand since the ELT IS conected to the Aircraft Power Why do I need to have a battery in the remote switch at all?? and could you not put in a charger system for the ELT battery as well???

Paul B
April 15, 2018


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 ...to 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.

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