Maintenance and Certification
- Emergency Locator Transmitter (ELT) Maintenance: Understand the Requirements and Watch for Loose Attachments
- TSB Aviation Safety Advisory: Insufficient Fuel Delivery Following Installation or Modification of Fuel System
Emergency Locator Transmitter (ELT) Maintenance: Understand the Requirements and Watch for Loose Attachments
The purpose of this article is to underscore the importance of observing proper ELT maintenance requirements and installation practices. This article also aims to inform manufacturers, owners, operators and maintainers of aircraft with fabric hook and loop ELT retention systems of the need to ensure adequate ELT retention in order to reduce the risk of potentially damaging the unit in the event of an accident.
An ELT is designed to detect that a crash has occurred and transmit a specific distress signal that is powerful enough to be detected by search and rescue authorities. In order to maintain ELT system reliability, there are maintenance requirements that need to be performed at specified intervals. These requirements are part of an aircraft’s approved maintenance schedule.
Non-water activated ELTs should be inspected at intervals not exceeding 12 months. ELTs powered by water activated batteries should be inspected at intervals not exceeding 5 years. Maintenance of an ELT system is typically carried out during an aircraft inspection phase. The inspection consists of an on-aircraft inspection, performance test, corrosion check, battery expiration verification, reinstallation of the ELT after maintenance and an operational check. The individuals performing these maintenance activities shall use the most recent methods, techniques, practices, parts, materials, tools, equipment and test apparatuses specified in the ELT manufacturer’s instructions, in equivalent instructions or in accordance with recognized industry practices. The ELT test equipment used to validate the performance of the ELT must meet the manufacturer’s specifications. Where the calibration specifications are published by the ELT manufacturer, the test equipment shall be calibrated by means traceable to a national standard.
NOTE: The ELT performance test must be done by an avionics-rated aircraft maintenance organization (AMO) with a radio rating and with the specific ELT model on its capability list.
Fasteners and attachments
Each ELT manufacturer has their own unique method of fastening the ELT to the aircraft. Due to the different types of fasteners like thumbscrews, metal latches, fabric hooks and loops, etc., the person performing the reinstallation should refer to the manufacturer’s instructions for guidance. It is essential that the ELT does not come loose or get ejected from its tray during a crash. Such a situation could cause the ELT to stop functioning and result in an unsafe situation that prevents the ELT from transmitting as designed.
Such a situation was discovered in a recent investigation by the Transportation Safety Board of Canada (TSB) following an accident, which is summarized in the “Recently Released TSB Reports” section of this issue of the Aviation Safety Letter (TSB Final Report A11W0151). The TSB noted during the field examination that the ELT was out of its mounting tray and hanging by the antenna cable. The remote control panel wires were broken near the ELT plug, and the antenna had been broken off by ground contact. As a result, no ELT signal was recorded by search and rescue (SAR) authorities nor was a 121.5 MHz signal received by SAR aircraft, even though the ELT was found to be operating when rescuers arrived on site.
The type of mounting system used on the accident flight consists of a rectangular composite tray affixed to the aircraft. The ELT rests within a raised box structure that goes around the perimeter of the mounting tray and is secured by a fabric strap featuring a VelcroTM hook and loop system. When the strap is tight, the ELT is firmly held in the mounting tray box (see Photo 1).
Photo 1: Properly mounted ELT with strap tightened
Field examination of the ELT and mounting bracket revealed that the retention strap was loosely fastened, and that it was possible to slide the ELT under the strap and back into its mount (see Photo 2). The unit could be easily removed in the same manner. Shortening the strap by ¾ inch tightened it around the ELT and secured the ELT to the bracket so that it could not be manually removed without loosening the strap.
Photo 2: ELT sliding under loose strap
The manufacturer’s instructions direct installers to align the strap buckle with the centre line of the unit and “fasten the self-stripping strap tightly”. There is no further definition of the degree of strap tightness required to adequately secure the ELT to the mounting tray. The subjective judgment of the installer is relied upon to make this determination.
As demonstrated in this occurrence, without clear instructions describing what constitutes a secure ELT installation, there is a risk that ELTs will be installed without sufficient strap tightness. During an accident, this may cause the ELT to fall out of its mount and separate from its antenna cable. Such an occurrence could prevent transmission of a distress signal, resulting in a delay of search activity, difficulty in locating the aircraft and delay in the rescue of occupants. This delay could adversely affect the level of occupant injury and survival. It could also cause the unnecessary diversion of search and rescue resources.
New Standard for 406 MHz ELTs
The Federal Aviation Administration (FAA) has determined that hook and loop fasteners are not an acceptable means of compliance to meet the mounting and retention requirements of technical standard orders (TSOs) for 406 MHz ELTs. As a result, on November 26, 2012 the FAA issued TSO-C126b which, among other requirements, withdraws TSO authorizations (TSO-C126a) issued for the manufacture of automatic fixed (AF) and automatic portable (AP) 406 MHz ELTs which incorporate hook and loop fasteners in their design. This action only affects future ELT installations. Transport Canada plans to adopt TSO-C126b into the Airworthiness Manual (AWM) to become a CAN-TSO-C126b design standard.
While it appears that hook and loop fasteners will gradually disappear, they may be around for a while yet. It is therefore important to follow the aircraft’s maintenance schedule and consult the ELT manufacturer’s instructions for additional information, such as how to properly install the ELT. Proper care of and attention to an ELT system remains the best way to safely locate a downed aircraft.
by Brian Clarke, Civil Aviation Safety Inspector, Operational Airworthiness, Standards, Civil Aviation, Transport Canada
Aircraft owners can apply to have their aircraft’s ‘normal’ certificate of airworthiness replaced by a Special Certificate of Airworthiness - Owner-maintenance. When an aircraft is in the owner-maintenance classification the aircraft owner—if they are a pilot—can perform and release maintenance on their own aircraft.
The first Special Certificate of Airworthiness - Owner-maintenance was issued in 2002 and there are now about 550 owner-maintenance aircraft registered, out of a Canadian non-commercial fleet of over 20 000 aircraft. The program is clearly not wildly popular, perhaps because owner-maintenance aircraft are not allowed by the Federal Aviation Administration (FAA) to fly in the United States. Nevertheless, questions to Transport Canada Civil Aviation (TCCA) related to owner-maintenance are frequent. The purpose of this article is to review some of the significant specifics on the subject of the owner-maintenance classification.
Under Canadian Aviation Regulations (CAR) Standard 507.03(6), the Special Certificate of Airworthiness - Owner-maintenance was established to allow the non-commercial use and enjoyment of relatively simple, generally older aircraft for which certified parts were scarce and support from the manufacturer limited. After the classification had been in place for a few years, owners of owner-maintenance aircraft were granted a Ministerial Exemption to CAR 605.03(1)(a), (b) and (c)—the requirement to have and carry a Certificate of Airworthiness. The exemption has the effect of allowing flight of an owner-maintenance aircraft that is no longer in conformity with its type certificate, and thus allows some degree of modification of the aircraft and the installation of equipment that was not specified by the manufacturer. The letter of exemption is carried aboard the aircraft and effectively becomes the aircraft’s airworthiness certificate. We refer to aircraft with a Special Certificate of Airworthiness - Owner-maintenance and those flying under the Exemption as “owner-maintenance classification” aircraft.
Owner-maintenance aircraft, just like other aircraft, have to be continuously maintained in accordance with a maintenance schedule conforming to CAR 605.86. Some maintenance tasks required by the schedule may require skills or equipment that the owner/pilot does not have; when the owner/pilot is not qualified or equipped to perform a required task, he or she can and should contract the work to a qualified person or organisation. In these instances, an Aircraft Maintenance Engineer (AME) or Approved Maintenance Organisation (AMO) can and should perform and release work on owner-maintenance classification aircraft.
Maintenance on owner-maintenance aircraft has to be performed in accordance with CAR 571.02, which calls for proper practices and use of the correct tools, manuals and instruments; records have to be kept in accordance with CAR 507.03 and 605.92. All modifications and repairs to owner-maintenance aircraft must be performed in accordance with at least “acceptable data”, as defined in CAR Standard 571.06. This may seem a lower bar than the “approved data” or “specified data” required for major modifications to aircraft maintained to a “non-Special” Certificate of Airworthiness, but it does not allow the unfettered installation of inappropriate parts or radical modifications.
CAR Standard 507.03(6)(e) lists the eligibility conditions for the owner-maintenance classification. An owner-maintenance aircraft cannot be modified beyond those limits. For instance, a constant speed propeller or amphibious floats cannot be installed on an owner-maintenance or “Exemption” aircraft, because the aforementioned standard limits eligibility to, among other things, aircraft with fixed pitch props and fixed landing gear. Significant modifications that affect the structural strength, performance, power plant operation, or flight characteristics of the aircraft have to be reported to TCCA before flight.
A Civil Aviation Safety Inspector (CASI) who is asked to consider the issue of the letter of exemption, or indeed any flight authority, has to verify that the aircraft is safe for flight. The determination that the aircraft is safe for flight is made by examining records and documents provided by the owner, but the CARs (and normal prudence) do not require that a CASI accept the owner’s declarations without review or confirmation. As a delegate of the Minister of Transport, the CASI has the authority to personally inspect or cause to be inspected any aircraft for which an application for flight authority has been made. Any personal inspection by a CASI of an owner-maintenance aircraft will be to the extent necessary to verify that the aircraft is as described in the documentation and is free of obvious defects.
In the simplest case of an aircraft having a valid Canadian Certificate of Airworthiness transitioning to owner-maintenance, a CASI’s inspection is very rarely required.
A CASI’s inspection will normally be conducted subsequent to unsatisfactory document review or if the aircraft is being imported, has not been operated in the last five years, or does not conform to its type design.
Aircraft can be imported directly into the owner-maintenance classification and an aircraft intended for owner-maintenance that does not meet its type design on import may be issued with the Ministerial Exemption mentioned above. Well-meaning people have come to the mistaken conclusion that the classification and exemption together allow the straightforward import and registration of disassembled aircraft, damaged aircraft and aircraft with incomplete technical records as well as heavily modified aircraft. This is not the case.
Consistent with the import requirements for other aircraft, it is reasonable for the Minister to require that an inspection up to equivalent-to-annual of the imported aircraft be carried out and if necessary that it be carried out by an AME. The CASI may require that a defect list be compiled and cleared, followed by inspecting the aircraft him or herself.
Lastly, it is important to note that while reversal of the owner-maintenance registration is possible it will not be easy or cheap.
Any questions you may have can be directed to a CASI at the Transport Canada Centre (TCC) most convenient to you.
Lists of aircraft that have been determined to be eligible for owner-maintenance classification:
Ministerial exemption to CAR 605.03(1)(a), (b) and (c):
Standard 507.03 — Issue of Special Certificates of Airworthiness
CAR 605.86 — Maintenance Schedule
CAR 571.02 — Maintenance and Elementary Work Performance Rules
CAR 605.92 — Requirement to Keep Technical Records
Standard 571.06 — Repairs and Modifications
To find the nearest TCC: www.tc.gc.ca/eng/regions.htm.
TSB Aviation Safety Advisory: Insufficient Fuel Delivery Following Installation or Modification of Fuel System
On July 25, 2012, a privately operated Quad City Challenger II advanced ultralight, equipped with a Rotax 582 engine, departed for a test flight from a private airstrip near Port Hope, Ont. During initial climb-out, approximately 18 s after full power application, the engine rpm reduced significantly and the aircraft turned back towards the airstrip. During this turn, the nose dropped steeply, and the aircraft impacted the ground in a wooded area south of the field. The aircraft was substantially damaged and the pilot, the sole occupant, sustained fatal injuries. The following safety-related information is derived from the Transportation Safety Board of Canada (TSB) Class 5 investigation A12O0113.
The aircraft was equipped with a MGL Avionics Enigma electronic flight instrument system (EFIS). This Avionics installation included a fuel flow sensor which contained an optional 1 mm jet orifice. The installation instructions supplied with the sensor describe a fuel flow range of 0.05–0.5 L/min with the 1 mm jet installed. A Rotax 582 engine at full power requires approximately 0.45 L/min.
The TSB could not determine if an adequate functional check of the aircraft fuel system had been completed prior to the occurrence flight. However, during a series of post-accident engine test runs, it was determined that a Rotax 582 engine, with the stock pneumatic fuel pump installed as it was on the occurrence aircraft, was only able to draw 0.24 L/min through the 1 mm orifice. As such, the engine was unable to run at full power for longer than 20 s.
The TSB notified the related avionics, airframe and engine manufacturers of the deficiency. MGL Avionics has released a Safety Notice regarding the Installation of Restrictor Jets in the Plastic Fuel Flow Sensor informing their customers not to use the 1 mm orifice without contacting MGL Avionics. The company now recommends using the 2 mm orifice for Rotax installations. However, the Rotax 582 installation manual calls for fuel lines with a minimum diameter of 5 mm and includes the instruction to never restrict normal fuel flow.
This fuel restriction disparity may not be limited to the manufacturers listed above and may be more widespread in the non-certified aircraft community. As this occurrence demonstrates, a functional check of the aircraft fuel system ought to be performed following a modification or new installation. Without such a check, pilots may attempt to operate aircraft with insufficient fuel delivery, thereby increasing the risk of engine failure. Awareness of this issue in the aviation community will hopefully help reduce the risk of a similar recurrence.
Invest a few minutes into your safe return home this summer...
...by reviewing important information on the use of the Pressure Altimeter, in Section AIR 1.5 of the Transport Canada Aeronautical Information Manual (TC AIM).
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