The Case for Replacing Legacy Electromechanical Flight Instruments with Modern Digital Displays

Introduction

The aviation industry is experiencing an increasing need to modernize its fleet due to the challenges associated with maintaining legacy electromechanical flight instruments. These challenges include poor reliability, high maintenance costs, and significant risks such as Controlled Flight Into Terrain (CFIT) and mid-air collisions. Modern digital displays offer enhanced reliability and additional safety features that can significantly mitigate these risks.

Supporting old components, such as the ADI-84, 329B-7R, AD-500 series, AD-600 series, and KCI 310 systems, is becoming increasingly difficult and expensive. These components have a low mean time between failure (MTBF) and substantial repair costs, making them less reliable and more costly to maintain. Furthermore, these legacy systems contribute to aircraft weight, impacting useful load and fuel efficiency.

The average operator can expect to pay upwards of $3000 per repair for those legacy instruments with lead times that often exceed 10 days for a replacement/repair part.

Background

History of Legacy Flight Instruments

Electromechanical flight instruments such as the ADI-84, 329B-7R, AD-500 series, AD-600 series, and KCI 310 systems have been in service for decades. These instruments were state-of-the-art at the time of their introduction but have become outdated with advancements in avionics technology.

• ADI-84: This attitude indicator has been a staple in many aircraft but has an MTBF of approximately 1,200 hours and an estimated repair cost of $3,000.
• 329B-7R: A directional gyro with an MTBF of 1,500 hours and a repair cost of $2,500.
• AD-500 Series: These instruments, including airspeed and altitude indicators, have an MTBF of 1,000 hours and repair costs ranging from $2,000 to $4,000.
• AD-600 Series: Improved versions of the AD-500 series with an MTBF of 1,200 hours and repair costs between $2,500 and $4,500.
• KCI 310: A course indicator with an MTBF of 1,100 hours and a repair cost of $3,200.

Maintaining these systems for an aircraft averaging 600 flight hours per year over ten years results in substantial life cycle costs. For example, the ADI-84 alone would likely need multiple repairs, potentially costing over $30,000 per instrument.

The average operator can expect to pay upwards of $3000 per repair for those legacy instruments with lead times that often exceed 10 days for a replacement/repair part.??With a useful Mean Time Between Failure of 1500 hours, and assuming the aircraft fly an average of 600 hours per year, a 20 aircraft fleet can expect to experience 80 grounding events and pay $2.4M in repair & replacement?costs over a 10-year?period.? That's?800 days?spent waiting for repair & replacement. Adjusting for 3% annual inflation this becomes $3.2M.??If you fly more than 600 hours per year, the downtime and costs will be higher.

On a global scale, CFIT accidents have resulted in an average of 30-40 fatalities per year over the last five years.

Controlled Flight Into Terrain (CFIT)

CFIT is a significant hazard in aviation, where an airworthy aircraft, under pilot control, unintentionally flies into terrain, obstacles, or water. ?The Aviation Safety Network (ASN) provides a comprehensive database of aviation accidents worldwide. According to ASN, CFIT accidents globally have shown a slight decline over the past five years, reflecting improvements in safety technologies and operational practices.? On a global scale, CFIT accidents have resulted in an average of 30-40 fatalities per year over the last five years. These accidents often involve a mix of commercial, cargo, and general aviation flights.

CFIT often results from a loss of situational awareness by the flight crew. This can be due to various factors such as poor visibility, complex terrain, navigation errors, or misinterpretation of flight instruments. When pilots are unaware of their proximity to the ground or obstacles, the risk of collision increases significantly.

CFIT incidents are frequently associated with flying at night or adverse weather conditions, such as fog, rain, or clouds, which can obscure the terrain and make visual navigation challenging. These conditions can further reduce the crew's ability to perceive and react to the terrain.

Reliance on outdated or malfunctioning navigation instruments can lead to incorrect altitude or position readings. Legacy electromechanical instruments may not provide the accurate and comprehensive data required for safe navigation, increasing the risk of CFIT.

Mid-Air Collisions

In the United States, the NTSB reports an average of 10-15 mid-air collisions per year in general aviation over the last five years.

Mid-air collisions, though less frequent, remain a critical safety concern. Mid-air collisions are generally more common in military aviation than in commercial aviation. Factors include less stringent ATC oversight, pilot error, aggressive maneuvering at high speeds, formation flight low to the ground, and less sophisticated onboard collision avoidance systems.

Since 2018, there have been several mid-air collisions involving military aircraft. The most notable incidents include the 2019 collision between French Army helicopters in Mali, resulting in the deaths of 13 soldiers, and the 2020 crash of two Indian Air Force fighter jets during a rehearsal for an air show. Other significant incidents include the 2021 collision of two UH-60 Black Hawk helicopters during a training mission in Utah, which tragically resulted in the deaths of three soldiers.

In the United States, the NTSB reports an average of 10-15 mid-air collisions per year in general aviation over the last five years. These accidents often involve small private aircraft operating under Visual Flight Rules in uncontrolled airspace.

Mid-air collisions often occur in complex airspaces where aircraft are operating in close proximity, such as near airports, during formation flights, or in busy airways. Pilots must rely on accurate situational awareness and communication to avoid collisions, and any lapse can lead to disaster.

Poor visibility, weather conditions, and other environmental factors can obscure pilots' view of other aircraft, increasing the risk of mid-air collisions. These conditions can make it challenging to maintain visual separation and situational awareness.

Weight and Fuel Efficiency

The weight of electromechanical avionics components directly impacts aircraft performance. For example:

• ADI-84: 6 lbs
• 329B-7R: 7 lbs
• AD-500 Series: 5-8 lbs
• AD-600 Series: 6-9 lbs
• KCI 310: 6 lbs

Replacing these instruments can significantly reduce aircraft weight, improving useful load and fuel efficiency. For instance, removing 40 lbs of outdated avionics from a UH-60 helicopter can enhance its payload capacity and reduce fuel burn, thereby extending range and operational efficiency.

Every 1% reduction in weight can result in approximately 0.75% to 1% reduction in fuel consumption

A Better Way

Modern Digital Aircraft Displays

Modern digital displays, such as the Nighthawk series, offer superior reliability and performance. These systems have significantly higher MTBF ratings, often exceeding 10,000 hours, and lower maintenance costs. Digital displays provide enhanced situational awareness, integrating various flight parameters into a single, easy-to-read format.

Terrain Awareness and Warning Systems (TAWS)

Mitigating the risk of CFIT requires the integration of advanced technologies such as Terrain Awareness and Warning Systems (TAWS), which provide real-time alerts to the crew about potential terrain conflicts. Additionally, modern digital flight displays offer improved situational awareness by integrating multiple data sources into a coherent and easy-to-understand format. Enhanced training and adherence to safety protocols also play critical roles in reducing CFIT incidents.

ADS-B In and Traffic Information Service Broadcast (TIS-B)

ADS-B In, coupled with TIS-B, provides pilots with real-time traffic information, significantly improving situational awareness and reducing the risk of mid-air collisions. These systems broadcast an aircraft's position and receive data from other aircraft, allowing pilots to see and avoid potential conflicts.

Weight Savings and Fuel Efficiency

The weight savings from replacing legacy avionics with modern digital displays can lead to significant improvements in fuel efficiency and useful load. For example, replacing old components in a King Air 200 with modern Nighthawk displays can reduce avionics weight by up to 50 lbs, translating to increased payload capacity and reduced fuel consumption.? According to aerodynamic principles and historical data on aircraft efficiency, every 1% reduction in weight can result in approximately 0.75% to 1% reduction in fuel consumption.[4] Additionally, for every gallon of fuel saved, a reduction of 21.1 pounds of CO2 gas can be realized.

Recommended Solution

Nighthawk SA-4550, SN-4500, and ST3400H

The Nighthawk series, including the SA-4550, SN-4500, and ST3400H, offers state-of-the-art avionics solutions designed to replace legacy electromechanical instruments. An AML STC (STC #ST01930LA) is available for direct replacement of the ADI-84, 329B-7R, AD-500 series, AD-600 series, and KCI 310 series.

• SN-4500: Offering modular convenience and flexibility, the SN4500 Primary Navigation Display is the standard in NAV displays. Incorporating patented LED backlight technology, the SN4500 is an ideal replacement for aging 4-in. and 5-in. electromechanical HSIs. With patented display engine generating a resolution of 200 pixels per inch—unmatched in the industry for brightness clarity, readability and color fidelity. ?Featuring Flight Plan Map, Traffic (TIS-B), and Weather (FIS-B) overlays, the SN-4500 offers an exponential leap in Situational Awareness. With an MTBF of 12,000 hours, weighing 3 lbs, and compared to the ADI-84, it offers a 75% improvement in reliability and a 50% reduction in weight.

• SA-4550: The SA4550 Primary Attitude Display is the perfect update for aging electromechanical ADIs, and an ideal complement to the high-definition SN4500 Primary Navigation Display. ?Featuring patented LED display technology, generating a resolution of 200 pixels per inch, the SA4550 provides 180° horizontal and vertical viewing angles. With an MTBF of 15,000 hours, weighing 4 lbs, this system offers a 90% improvement in reliability and a 43% reduction in weight compared to the 329B-7R.

• ST3400H: ST3400H HeliTAWS? is the industry’s first multihazard avoidance system for helicopters that alerts against wires, terrain, and obstacles, utilizing WireWatch?—advance defense against wire strikes. It further enhances the operational awareness in the cockpit by helping helicopter pilots avoid transmission lines whether they are powered on or off.? Incorporating proprietary TruAlert? technology, HeliTAWS enables pilots to take off, cruise, hover and land at off-airport locations without triggering nuisance alerts.? HeliTAWS includes an easy-to-interpret, color, high-resolution display for 3D terrain, obstacles, flight plan, TIS-B traffic overlay, ADS-B In, Radalt Decent Altitude Callouts along with On-Demand NVIS compatibility.? The ST3400H Incorporates automatic or manual engagement of Offshore HTAWS modes, improving safety margins for offshore helicopter operations. With an MTBF of 14,000 hours, weighing 5 lbs, it replaces multiple instruments from the AD-500 and AD-600 series, providing an 85% improvement in reliability and a 30-50% reduction in weight.

This is a savings of over $50,000 in repair costs, per aircraft, over a 10 year period.? A fleet of 300 aircraft would see savings of over $15M.? The total weight savings is 28-38 lbs.? Using 35 pounds, the fuel savings for a King Air 200 burning 400 lbs per hour and flying 600 hours per year would be 675 lbs per year.

System MTBF and Weight Savings

Calculating the estimated system MTBF for old components versus new Nighthawk replacements highlights significant improvements:

• Legacy System MTBF: Approximately 1,200 hours
• Nighthawk System MTBF: Approximately 13,000 hours

Weight savings by replacing old components with Nighthawk components:

• Legacy System Weight: 40-50 lbs
• Nighthawk System Weight: 12 lbs

This is a savings of over $50,000 in repair costs, per aircraft, over a 10 year period.? A fleet of 300 aircraft would see savings of over $15M.? The total weight savings is 28-38 lbs.? Using 35 pounds, the fuel savings for a King Air 200 burning 400 lbs per hour and flying 600 hours per year would be 675 lbs per year.

Conclusion

Modernizing aircraft avionics by replacing legacy electromechanical flight instruments with digital displays offers numerous benefits, including improved reliability, reduced maintenance costs, enhanced safety through advanced situational awareness, and significant weight savings. The Nighthawk SN-4550, SA-4500, and ST3400H provide state-of-the-art solutions that enhance aircraft performance and safety. These advancements not only reduce the risk of CFIT and mid-air collisions but also contribute to increased useful load and fuel efficiency, making a strong case for transitioning to modern digital avionics systems.

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For more information on Nighthawk Flight Systems products & services, please visit www.nighthawkfs.com or contact us at [email protected]

Sources:

[1] Nighthawk analysis. Data pulled from multiple sources and is illustrative of likely results.

[2] Source data from Aviation Safety Network (ASN), International Civil Aviation Organization (ICAO), National Transportation Safety Board (NTSB) and Federal Aviation Administration (FAA) databases.

[3] Source data from Aviation Safety Network (ASN), International Civil Aviation Organization (ICAO), National Transportation Safety Board (NTSB) and Federal Aviation Administration (FAA) databases.

[4] NASA technical reports.? Studies on aircraft weight reduction and fuel efficiency correlation