Reprinted from Depot-Level Support to the CH124 Sea King by Terry Robbins
Introduction
That the Sikorsky CH124 Sea King has met the milestone of 50 years of service in the Canadian Forces (CF) is not happenstance. Decisions were made by the uniformed engineers in Ottawa in the 1970s and 1980s that have paid off in a way that can only be measured by the fact that the Sea King remains in airworthy operation in the year 2013. Those forward thinkers were the senior Aeronautical Engineering (AERE) officers who resided in the Director General, Aircraft Engineering and Maintenance (DGAEM) organization, the direct IMP Aerospace engineering customer. Their foresight and contributions to the maritime fleets of aircraft must be acknowledged, especially so on the CH124 Sea King, which went into a depot-support programme at IMP Aerospace and benefitted from the work started by Director, Maritime Aircraft Engineering and Maintenance (DMAEM) staffs. One can point to sustained initiatives during the 1975–1985 era in which the Department of National Defence (DND), working hand-in-hand with the engineering community at IMP Aerospace, created the nucleus of an engineering-support capability within IMP Aerospace that readied the company to accept engineering cognizance, and the production work that followed, for the CH124 in the mid-1980s.
IMP Aerospace
IMP Aerospace has been involved with domestic and international Sea King repair and overhaul, parts/components manufacture, engineering, publications and logistics support for 30 years. IMP Aerospace is a full-service aerospace company, with Aerospace, Avionics and Aerostructures divisions. IMP Aerospace has over 1,500 employees, providing engineering, technical, materiel and support expertise. It has an ISO 9001-registered quality system andholds Accredited Maintenance Organization and Accredited Technical Organization approval from both the CF and Transport Canada. IMP Aerospace provides complete life-cycle support services, including engineering, integrated logistics, publications management and asset management. IMP Aerospace is a Sikorsky authorized service centre for the manufacture of S-61 sheet-metal parts and is the Hamilton Sundstrand world-wide licensee for the repair of the Sea King automatic stabilization equipment. IMP Aerospace has developed a broad range of expertise in support of aging aircraft.
IMP Aerospace became involved with the depot-level support to the Sea King as part of the Repatriation of Sea King Depot Level Support (ROSKDLS) programme. The Sea King Replacement Program Office was established in 1978; its intent was to field a replacement aircraft within a reasonable time frame. In 1980, Pratt and Whitney Canada, a sister division of Sikorsky Aircraft Corporation and the provider of depot-level support to the helicopter, determined there was no future in Sea King support. They were also developing the PT-6 engine at the time, which was drawing manpower and resources away from the helicopter programme. DND then went looking for a new service provider who would also be acceptable to Sikorsky; Sikorsky refused to allow the Sea King technical data package to fall into the hands of their competitors, so a non-aligned aerospace company was required. In 1982, IMP Aerospace became the engineering and depot-level maintenance contractor for the Sea King, while SPAR Aerospace became the dynamic component overhaul contractor. DND bought the technical data and drawings and entered into a technical assistance agreement with Sikorsky for data updates and engineering assistance. IMP Aerospace became the engineering-cognizance contractor and holds the technical data set. They also established a depot-level capability for the aircraft and selected components. IMP Aerospace Production staff doubled in size—there was no lack of retired military personnel who were Sea King trained and willing to stay in the Halifax area. IMP Aerospace Engineering staff increased by 50 per cent. These individuals had to be recruited and trained.
The Value of an Overhaul Contractor
Those who have not been associated with depot-level support to military fleets of aircraft like the Sea King do not always recognize the roles played by those agencies, but they can be readily identified. They form the framework behind the argument that selecting and staying with one overhaul contractor is the most effective means of obtaining long life from an aircraft: squadrons move; operating bases change; military personnel move through their system; governments change; government departments evolve; maintenance resources at operating bases (both human and otherwise) rise and fall irrespective of operational needs; maintenance practices change; original aircraft manufactures develop new products and, for economic reasons, drop support to their older aircraft; technology changes; and operational roles of aircraft change and, hence, the aircraft themselves change. In all, the environment in which fixed- and rotary-wing aircraft operate is in constant flux, and the effects are disruption and loss of control. The results can be seen in the compromise of a country’s military capability: in-service fixed- and rotary-wing aircraft that cannot be supported sit on the ground. Therefore, the most important role of depotlevel contractors is this: they provide the knowledge base and the continuity which otherwise would be lost in this sea of constant change.
In-service but out-of-production aircraft quickly become logistics nightmares. However, IMP Aerospace had cut its materiel teeth for ultimately supporting the Sea King on their work on both the CP107 Argus and CP121 Tracker fleets during the 10 or so years prior to assuming the long-term depot-level support of the CH124. Approved sources of qualified parts, awareness of the pitfalls of bogus parts, integration with the Canadian Forces Supply Systems and engineering methods for qualifying alternative parts or designing around the problem had been established well in advance of the challenges of supporting the Sea King. As anyone in the industrial or government materiel world will attest, out-of-production and long-in-the-tooth aircraft present challenges, as the acquisition of replacement parts can bring grown men to tears, usually because of the cost of work-arounds. “Work-around” often means engineering redesign, and redesign in the aerospace industry does not come cheaply. If anyone in the aircraft support world deserves recognition, logisticians should be close to the top of the list. Similarly, production workforces in a depot facility will, without much encouragement, patiently explain why their jobs on the hangar floor are not exactly a walk in the park. They and their supporting departments are all unsung heroes.
Unsupported technical documentation can be a serious problem, bordering on a flight-safety issue. Intermittent attention to this most fundamental requirement — and/or the moving of the responsibility around from agency to agency — is horribly disruptive and terribly expensive. The solution rests with the overhaul contractor. Well aware of this from their Tracker experience and observing the need for rescue of the Sea King technical documentation set, two initiatives came from IMP Aerospace in that regard, both of them aimed at cleaning up a serious problem with Sea King documentation.
The master drawing set for the CH124 when IMP Aerospace inherited support of the fleet was, in a word, unusable. Through no fault of anyone in particular (the Sea King was going out of service, right?), the only official documentation for the aircraft consisted of original drawings from previous companies upon which had been stacked change data in such quantities over such a prolonged period of time and in such a convoluted manner that the effort consumed in making engineering decisions was huge and the risk of error great, particularly when dealing with aircraft structures and electrics/avionics. There were change notes on top of change notes on top of prior change notes that, for those with patience, would ultimately track to the original drawings. That led to IMP Aerospace taking over the CH124 master drawing set and incorporating collections of accumulated changes. That was a major programme, chipped away at with DND support over a period of years. In many, many cases, it involved the recreation of the original data by new drawings with the changes incorporated and the drawing change history retired to the archives.
As it was for the Sea King master drawing set, so it was for the CH124 Canadian Forces Technical Orders (CFTO): they were of dubious integrity. Even Maintenance Instructions for the Canadian Navy (MICNs), for those who remember those documents, were necessary to support the helicopter in the field. That situation came to a head during the rewiring of the fleet — neither the aircraft drawing set nor the CFTO wiring diagrams bore much resemblance to the real world. The longer-term net result of this situation was the assumption by IMP Aerospace of responsibility for the creation and upkeep of CH124 technical publications set — including the Aircraft Operating Instructions — and significant growth in the rudimentary capability that had been developed for support of the CP121 CFTOs. IMP Aerospace produced, and continues to produce, CH124 CFTOs.
Engineering Support
The other benefit a depot-level support organization provides is that of a stable, long-term engineering organization — the lead effort for depot-level support starts in the engineering community. At IMP Aerospace, that engineering work began with the CP121, primarily as the result of the very successful Tracker Surveillance Update Program, a huge and challenging undertaking by all concerned at that early point in IMP Aerospace’s time, since it involved the prototyping of some systems that had yet to see any previous airborne application. That is where IMP Aerospace learned its systems-integration skills and developed (however rudimentary, then) the methods and processes associated with support of aircraft avionics and electrical systems that continue to this day. The core engineering concept was subsequently expanded to embrace the CP107 Argus, then nearing the end of its useful life, yet from a structural perspective, it was still expected to fly safely. Introduction of the CP140 Aurora represented an incremental improvement in the development of core engineering skills within IMP Aerospace, again supported fully by the engineering community in Ottawa. Even before the first CP140 aircraft delivery, IMP Aerospace engineering was heavily involved in the induction process, working hand-inhand (and on site) with Lockheed. This provided a firm foundation for the formal introduction of the Aurora to the plant. Thus, when the opportunity presented itself to introduce the new rotary-wing programme into IMP Aerospace, the engineering transition was more-or-less seamless. It was a matter of cloning known effective methods and processes, and organizations, along with supplementing the formal management procedures and updating Approvals and Quality Program documentation. ISO 9001 approval was subsequently obtained on the basis of them. Furthermore, although IMP Aerospace was still being exercised on a task-by-task basis, the company had already successfully undertaken a broad range of engineering projects and subsequent production work for the CH124 helicopter: the records show that 39 projects were on the books before the first hint can be found (in 1982) of the formal move of in-service depot-level support of the helicopter to IMP Aerospace. By the time that IMP Aerospace was awarded the responsibility for providing depot-level support to the Sea King, all the engineering and other skills were already in place, and the company was ready. Thereafter, the size and composition of the skill set within engineering has grown in direct proportion to the needs of the helicopter.
Depot-Level Support and Modifications
In 1963, the Royal Canadian Navy started taking delivery of 41 Sikorsky Aircraft Corporation Sea King helicopters for antisubmarine warfare (ASW) operations. As of this writing, there have been 813 field-level modifications and 498 contractor-depot modifications developed and incorporated into the aircraft. These modifications range from simple part substitutions to equipment / system upgrades to three complete role changes. This paper will not discuss all the modifications, only those contractor-level modifications which had a significant operational impact or improved the structural strength of the aircraft. The first modification occurred in 1965 when the auxiliary flotation bags were added.
During 1965 to 1967, equipment improvements included removing the AN/ASA-13 navigation system and installing the AN/APN-503(V) Marconi Doppler navigation system, installing the 618T-2 high frequency (HF) radio system, replacing the AN/ARN-52(V) with the AN/ARN-501 (V) TACAN (tactical air navigation) system, retrofitting the AN/AQS-10 with the AN/AQS-13 sonar for improved ASW capability, and structurally reinforcing internal bulkheads where cracks had been found (more on this later).
During 1969 to 1970, equipment improvements included installing the AN/ASN-501 tactical navigation computer; installing the engine foreign object damage (FOD) deflector (referred to as the FOD mod) to improve engine reliability; and strengthening various areas on the airframe, including the tail probe attachment, main transmission support structure, the upper left-hand tail cone hinge and a bulkhead. The lower personnel door latching system was improved to prevent accidentally opening the door. This resulted from an incident where a passenger fell from a helicopter in flight. The interim solution to the problem, which remains to this day, was the “Barker Bar,” named in honour of the man who fell from the aircraft and was safely returned when he was discovered clinging to the sponson.
The year 1975 saw the beginning of the Sea King Improvement Program. This program included upgrading the General Electric T58-8B to the T58-8F engine (generating 1,350 shaft horsepower [1,006.7 kilowatts at the rotor head] and increasing the all-up weight (AUW) to 20,500 pounds [9,298.6 kilograms]) and installing main and tail rotor de-icing (subsequently removed), a low rotor revolution per minute (RRPM) warning system, the AN/APS-503 radar and the AN/APQ-501 Radar Altimeter Warning System (RAWS). Structural improvements included installing a steel upper tail cone hinge fitting, beefing-up the sponson stub wing, reinforcing the sponson main landing gear structure, reinforcing internal bulkheads and installing stronger landing gear drag links to withstand destroyer deck landings, as a result of a crash on the deck.
During 1977 to 1979, the Sea King Omnibus Modification Program began. This included the change from a forward-facing seating arrangement for the navigator and sensor operator and installing the sideways-facing console. This was intended to aid in crew coordination and safety. The programme also encompassed the installation of the AN/AQS-502 dipping sonar, Bathythermograph and On-top Position Indicator to improve the ASW capabilities. The AN/APX-77 Radar Identification System was installed to provide a crypto-secure radar identification capability. Chutes for internal stores carriage were installed — no more throwing smoke markers or signal-underwater sound (SUS) charges out the window! Structural changes included improvements to the tail-wheel support assembly to prevent cracking and installation of the In-Flight Blade Integrity System (IBIS) due to concerns with cracking of the main rotor blade spar. In this system, the spar is pressurized, and a radioactive source is uncovered if the blade pressure drops. The radiation is detected by a sensor, which gives the pilot an indication of the pressure drop. Due to the short period from crack initiation to catastrophic failure, a blade with a conventional blade inspection method has to be shut down and visually inspected every 12 hours. The IBIS allows unlimited flight time.
The next block improvement occurred from 1981 to 1984, known as the Sea King Update Program. AN/ARR-52A sonobuoy receivers were installed to provide sonobuoy receiving capability, including racks for carrying up to 18 sonobuoys. AN/ARC-511 very high frequency (VHF) amplitude modulated (AM) and AN/ARC-513 VHF frequency modulated (FM) radios were installed to provide expanded communications capability. A KY-28 secure voice system and a crash position indicator were installed; the AN/APN-171 radar altimeter replaced the AN/APN-117.
Nineteen eighty-four saw the commencement of the depot-level inspection and repair (DLIR) programme at IMP Aerospace. This was the first DLIR for the aircraft since they had been delivered to the Royal Canadian Navy. The primary purpose of the DLIR was to perform a systematic, in-depth inspection for, and repair of, corrosion. All of the aircraft systems, including the floorboards and fuel cells, were removed. At this time, the paint was changed to a low-gloss polyurethane paint. The DLIR also provided an opportunity to completely rewire the aircraft. Inspection of the wiring revealed insulation break-down, sleeving cracking and numerous splices. The many no-fault-found system problems and consequent mission losses were attributed to the condition of the wiring. The rewire used MIL-W-23795 wire and MIL-C-27500 cable (which were modern, much more robust wire specifications than originally used) and remain on the aircraft to this day. The wire harnesses were designed and installed at IMP Aerospace and were manufactured at IMP Avionics Division. When the prototype rewire Sea King was received in plant, IMP Aerospace found it necessary to design a new wire harness: this was accomplished by Production removing old harnesses, documenting the interconnection as found on the aircraft, and feeding the raw data to Engineering for use in new design. The success of this programme led to IMP Aerospace implementing a similar programme for the Egyptian Air Force Sea Kings from 2003 to 2006. DLIR also saw the replacement of most of the fuselage fittings with 7075 T-73 aluminum. The original T-6 aluminum fittings, while slightly stronger, were prone to stress corrosion cracking. Although this problem was never confirmed on the Sea Kings, good stewardship demanded this change be made. The DLIR has become an ongoing programme, thus ensuring the airworthiness of the Sea King and significantly contributing to its long service life.
Nineteen eighty-four also saw the commencement of the Automatic Stabilization Equipment (ASE) Reliability Improvement Program. At that point, the ASE mean time between failure (MTBF) was approximately 4 hours—essentially, one could expect the ASE to fail on every flight. IMP Avionics Division had acquired the worldwide licensing rights for the ASE from Hamilton Sundstrand and, thus, had the technical data required to address the problem. As with most Sea King issues, price was a strong determinant of the likelihood of a programme being funded. In this case, the engineers determined that the problem could be rectified by simply stripping all the parts off the boards and replacing them with new items—only obsolete parts were updated. As a result of this work, the ASE mean time between failure rose to 400 hours. Based on the success of this, IMP Aerospace conducted a similar programme for the United States Navy (USN) Sea King fleet in 1993.
The years 1986 to 1989 brought the installation of the Helicopter Acoustic Processing System (HAPS). This system consisted of a SBP4-1 (AN/UYS-503) acoustic data processor, an AN/ASN-123 tactical navigation system, an AN/ARR-75 sonobouy receiver, an M14-E tape recorder and the interfacing equipment. It was installed only on CH12411, which was subsequently lost at sea due to loss of the main gearbox oil. The full fleet had the AN/APN-503 Doppler system replaced with the state-of-the-art AN/APN-513 Doppler radar set. This new Doppler system allowed the fleet to return to night-hover operations from which they had been restricted due to safety concerns with the old system. To improve the low-speed directional control, especially the right sideways movement, a strake was fitted to the left side of the tail cone. The strake broke the symmetry of the airflow over the tail cone, essentially turning it into a wing. This reduced the power required at the tail rotor to maintain straight flight. Operational capability was improved by replacing the outdated AN/ARC-552 ultra-high frequency (UHF) radio with the AN/ARC-164 (V) UHF radio and replacing the KY-28 with the KY-58/KY-78 secure voice system. Crew safety was improved with the installation of an improved low RRPM warning system. The requirement resulted from the flight safety investigation into the crash of the waterbird. The installation was designed by IMP Aerospace; it produced a higher volume and progressively faster beep rate as the RRPM dropped. The crashed waterbird aircraft (CH12425) was also rebuilt. During this period, an engine firewall web was reinforced to prevent cracking.
The summer of 1990 provided perhaps the greatest challenge the Sea King operational, maintenance and engineering communities ever faced. In response to the United Nations mandate to remove the Iraqi military from Kuwait, Canada offered to provide three ships for interdiction and control duties in the Persian Gulf. This required that six Sea Kings be reconfigured from an ASW to surface-surveillance role in 10 working days. The ASW equipment was removed, but the wiring, fittings, etc. were left in place should an ASW threat arise. A self-defence suite — consisting of an AN/ALQ-144 infrared countermeasures system (bottom mounted), M130 chaff and flare dispenser, AN/ALE-37 Electronic Countermeasures Dispenser and AN/APR-39(V) Radar Warning Receiver — was installed. Other systems included a forward looking infra-red (FLIR) 2000 system, Trimble Trimpack global positioning system (GPS), C9 light machine gun (5.65 millimetre), laser warning receiver, and aircrew seat pan armour. Considered but not installed due to time, procurement or testing constraints were the AN/AAR-47 Missile Approach Warning System, KY-75 HF Secure Voice, AN/ARC-164 Have Quick Modifications and AUTOCAT UHF Relay. Ten minor aviation life support equipment (ALSE) and safety systems modifications were carried out concurrent to the aircraft modification activity.
From 1992 to 1995, the CH124B was introduced; it was a CH124A from which all the active ASW equipment was removed and replaced by the Helicopter Towed Array Support (HELTAS) system. The system consisted of an AN/UYS-503 acoustic processor / sonobouy command system, AN/ARR-75 sonobouy receiver system, AN/ARC-164 UHF radio, AN/ASQ Advanced Integrated Magnetic Anomaly Detector in the tail cone, the AN/ASN-123C tactical navigation system and sonobouy stowage rack. Also installed were an M14-E tape recorder, a time code generator and a Magnetic Anomaly Detector (MAD) chart recorder. The purpose of the HELTAS system was to work with ships equipped with CANTASS (Canadian Towed Array Sonar System) to enable operational training and development of passive acoustics tactics in anticipation of the arrival of the Sea King replacement helicopter.
During this same period, frequent cracking of the aluminum upper pylon hinge fitting was experienced. In order to reduce the inspection and maintenance burden, a steel fitting was installed. In keeping with the adage that no good deed goes unpunished, the added weight of the steel fitting pushed the already aft-tending centre of gravity of the aircraft to one in which certain manoeuvres and fuel loads resulted in an out-of-tolerance condition. To correct this, IMP Aerospace developed a centre of gravity improvement modification, which relocated avionics components forward into the electronics bay. This resulted in the forward shifting of the basic centre of gravity by approximately 4 inches [10.2 centimetres] and a return to the aircraft flying like it used to.
From 1997 to 1998, in an effort to increase capability and commonality, the CH124A had the same AN/ASN-123C tactical navigation system as the CH124B installed, and the CH124B had the same FLIR system as the CH124A installed. Both models had the AN/ARN-127 VHF Omnidirectional Range / instrument landing system (VOR/ILS) navigation system installed. Both models also had an electric wiper/washer system installed, replacing the no-longer-supportable hydraulic system. The lower aft sponson support fittings were replaced with a fitting which had thicker lugs, allowing for more rework before the fitting required replacement.
In 1999, a major structural modification, known as the Centre Section Replacement Program, was undertaken to replace the main lift frames. Web cracking, which was first discovered in 1972, was a common problem. Repair schemes were developed and incorporated, but the cracking continued to the point that there started to be repairs on the repairs, making the design and analysis very difficult. In 1994, IMP Aerospace produced a report on the condition and status of all the aircraft. It found that airframe hours ranged from 6,000 to 10,000; there was no correlation between the presence of cracks and the Bureau Number (i.e., the cracking seemed to be randomly spread about the build sequence), and airframes had anywhere between no cracks to five cracks. The report found 4 aircraft with cap angle cracks and 27 with web cracks. DND followed the USN approach and replaced the centre section on the fleet. This replacement was based on the Sikorsky design that was developed for the USN. IMP Aerospace adapted the modification to meet the requirements and peculiarities of the Canadian Sea Kings. The programme consisted of replacing the affected main lift frames from the floor level up and installing new main gearbox and sponson mounting fittings. This programme essentially restored the most highly stressed portion of the airframe to an as-new condition.
During the same period, an IMP Aerospace initiative to improve an internal bulkhead to prevent cracking was undertaken. There was a long history of cracking of the “T” fittings which are used to attach the tail cone to the aft fuselage. While the cracks did not pose a serious issue to safety of flight, there was a considerable maintenance and aircraft unavailability burden associated with the repairs. The USN and Royal Navy solution was an aluminum strap which reinforced the joint. This had the consequence of adding considerable aft weight — not good — and making tail cone removal very difficult. IMP Aerospace investigated the problem and determined that imprecise alignment of the “T” fittings during assembly was resulting in a preload and, hence, higher stress on the fittings, resulting in overload and cracking. The solution developed consisted of jigs for both the fuselage and pylon, which ensured perfect alignment of the fittings. There has been next to no cracking found since this programme was instituted.
In the 1999 to 2002 period, two significant upgrade programmes were undertaken. Parts for the T58-8F engine were becoming scarce, as many military operators shifted to the T58-401 version of the engine. The overhaul provider for the CF Sea Kings proposed that the engines be converted to the commercial CT-58-100. This conversion resulted in an increased available power to 1,500 horsepower [1,118.5 kilowatts] and improved availability of parts.
In October of 1996, Sea King 12424 lost power and crashed on the deck of HMCS HURON. The flight safety investigation concluded that the loss of power was possibly the result of a phenomenon known as “freewheel roller spit out,” wherein the freewheel unit momentarily loses the ability to transmit engine power to the main gearbox. The solution to this was to install the 24000 Series main gearbox, which commenced in 1999. This main gearbox had changes which improved the freewheel unit reliability; included an emergency lubrication system which provided an improved probability to land safely in the event of lubrication oil loss; strengthened certain gears and housings; and had external filter bowl attachment bolts, addressing an earlier problem with filter bowl retention.
During this period, the C6 General Purpose Machine Gun (7.62 millimetres) was installed. Also, the aircraft-side sponson attachment fittings were replaced (on an attrition basis) with items having thicker lugs, enabling more rework before the units required replacement.
In 2000, the CF introduced a completely new system of airworthiness. One of the consequences was the requirement for technician training to include a minimum of 5 per cent hands-on work on the aircraft. To meet this stipulation, an otherwise operational aircraft was permanently assigned to 406 (Helicopter Training [HT]) Squadron as a maintenance trainer. In 2004, CH12401 crashed on deck. IMP Aerospace inspected the aircraft and determined that it was feasible to rebuild it as a category one maintenance trainer, allowing the aircraft at 406 Squadron to return to the operational fleet. To meet the requirement as a maintenance trainer, it had to be safe to apply electrical power to the aircraft and all avionics and mechanical components had to be installed. The essential structure was replaced, and non-airworthy repairs were installed where possible (e.g., in the boat hull area where personnel did not go.) All non-airworthy repairs were recorded in case the aircraft had to be rebuilt as a flyer. To shorten the time required to accomplish the rebuild, IMP Aerospace requested, and was approved, to use parts from a USN SH-3 which was in the process of being struck and scrapped. The structural parts from this aircraft were used in the non-airworthy repairs.
In January of 2006, the CF began discussions and feasibility evaluations on the development of Standing Contingency Task Force (SCTF) which would require the use of Sea Kings in a troop-transport and utility-support role. A decision was made that the five remaining CH124Bs would be converted for this role. While not quite of the same magnitude of change, and certainly with a longer developmental time frame (eight months for design, installation and delivery of the aircraft) than the Operation FRICTION programme, the SCTF nonetheless required a solid focus on the goal by IMP Aerospace Engineering, Production and Material Departments. The role change consisted of removing all the passive acoustic sensor equipment and the internal stores system. To be installed were 14 crashworthy seats; equipment-securing nets (an army platoon carries an incredible amount and variety of equipment); an entrance step and handholds to ease the loading and disembarkation of the troops; a cabin liner to prevent snagging of equipment; and three overhead crew restraints to replace the single, floor-level restraint. An AN/ARC-210 multi-band radio for communications was also installed, based upon an Aerospace and Telecommunications Engineering Support Squadron (ATESS) design. The major design constraints were the requirement for 14 seats (so a platoon could be carried in two helicopter lifts) and that the side-facing console had to remain installed. This required some interesting engineering approaches to get the seats sufficiently forward to keep the centre of gravity within limits.
Based on an Australian Sea King crash in which the passengers were killed, the CF Flight Safety branch mandated the installation of crashworthy passenger seats in the CH124A fleet. The seats and installation design were based on the CH124B troop seats, with some changes to the underfloor design to enable the modification to be incorporated without removing the fuel cells. At the same time, the CH124B seat attachments were modified so three seats could also be installed in the same position as in the CH124A, allowing a common bathtub to be fitted.
While investigating a problem where engine power would suddenly drop, an instrument panel video monitoring system (IPVMS), consisting of a video camera in the cockpit to record the flight instruments and a tape recorder to save the data, was installed. In 2006, an IPVMS upgrade was designed which replaced the tape recorder with a digital recorder. The intercom system was also fed into the recorder to serve as a cockpit voice recorder. In 2009, the Sea King lighting system was modified with filters, lenses and lights to make it night-vision-goggle compatible.
From 2010 to present, the approach has been to not spend money on the Sea King, as it is going away. Slippage of the CH148 Cyclone delivery schedule, however, may result in Transport Canada mandating the installation of a 406 megahertz (MHz) emergency locator and a 406 MHz crash position indicator. The installation of the AN/ARC-210 multi-band radio in the CH124A is a potential capability improvement.
Conclusion
As can be seen from the above, while a superficial glance at a current Sea King doesn’t show much change from the 1963 Sea King, considerable effort has been expended to improve the safety, reliability, maintainability and operational effectiveness of the helicopter in its 2013 form—that’s 50 years after having been extruded through the doors of Pratt and Whitney Canada. This success story is a perfect example of the happy confluence of a number of organizations which came together to pursue a common goal. It was the capability that developed from those drivers that became the depot-level support programme for the Sea King, a clearly invaluable contributor to sustaining one of Sikorsky’s most successful products.
Terry Robbins
Terry Robbins has 35 years’ experience in the management of aircraft and weapon systems engineering, including design, modification, testing as well as repair and overhaul. Of that, 24 years has been in direct association with the Sea King helicopter in both military and civilian functions.
Terry began his career at 12 Wing Shearwater, serving as a first line Sea King maintenance officer at 423 Maritime Helicopter Squadron that included an operational deployment aboard Her Majesty’s Canadian Ship (HMCS) PRESERVER. This was followed by a staff position in National Defence Headquarters (NDHQ), a technical services detachment quality assurance role at IMP Aerospace and a second posting as the Air Maintenance Officer in HMCS PRESERVER. It was then back to NDHQ where he broadened his experience in project management and engineering support as the Sea King Aircraft Engineering Officer. His efforts there were rewarded with a most enjoyable tour as the H 3 Project Officer on exchange with the United States Navy at the Naval Aviation Depot (NADEP) in Pensacola, Florida. His last military posting was as Systems Engineering Manager for the Maritime Helicopter Program.
His first civilian job was with SPAR Aviation Services, where he supported the repair and overhaul of dynamic components for the Sea King fleets of the Canadian Forces, United States Navy, Brazilian Navy and Royal Malaysian Air Force. This was followed by a move to IMP Aerospace in Halifax, where he established the maintenance programme for the Cormorant search and rescue helicopter. He then spent several years as the Engineering Manager for the rotary-wing programmes, providing engineering services in support of the Sea King and Cormorant. He is currently employed as a proposal manager.
Terry has a degree in Mechanical Engineering from the University of New Brunswick. During his military career he received the Chief of the Defence Staff Commendation for his leadership in preparing the Sea Kings for Operation FRICTION and the Secretary of the United States Navy Commendation for his work at Naval Aviation Depot, Pensacola.