A series of rigorous acoustic certification tests has been initiated by Russia for its import-substituted SJ-100 passenger aircraft, which are fitted with domestically developed PD-8 turbofan engines. The program is intended to determine whether the aircraft complies with international noise standards for civil aviation, a critical prerequisite for its eventual operation on international and Russian airport networks.
Specialists from Yakovlev, which is a subsidiary of the United Aircraft Corporation (UAC), are conducting the tests in collaboration with the M.M. Gromov Flight Research Institute (LII). The evaluation concentrates on the noise produced during takeoff and landing, when aircraft engines function at relatively high thrust levels and ground-level noise exposure is particularly significant.
Although the PD-8 engine has undergone a comprehensive certification program of its own, the SJ-100’s installation of the engine necessitates the complete aircraft configuration to demonstrate compliance with the relevant noise regulations. This is a critical phase in the certification of Russia’s passenger aircraft that are imported and substituted.
The Importance of Aircraft Noise Certification
In modern civil aviation, aircraft noise is a major factor to consider. In recent decades, international aviation authorities have gradually tightened the regulations that govern the noise generated by passenger aircraft in the vicinity of airports. These standards aim to mitigate the effects of aviation operations on nearby communities.
Through its environmental protection framework, the International Civil Aviation Organization (ICAO) establishes international standards for aircraft pollution. Before receiving the appropriate certification, aircraft manufacturers must demonstrate that their aircraft conform to the relevant noise limits.
The access of an aircraft to airports that operate under the prescribed standards may be restricted if the aircraft fails to meet the standards. As a result, noise performance is not only a factor that impacts the commercial operating potential of an aircraft but also an important environmental consideration.
The issue is especially pertinent for the SJ-100, as the aircraft is being developed as a replacement for the original Superjet configuration, which features Russian engines and a substantial domestic supply of components and systems.
Atmospheric Conditions Must Be Precisely Controlled
The propagation of sound is depends upon atmospheric conditions, which is one of the most difficult aspects of acoustic certification. The transmission of aircraft noise from the aircraft to ground-based measuring equipment can be influenced by environmental parameters such as temperature, humidity, and wind speed.
Consequently, it is impossible to conduct acoustic measurements in the presence of unpredictable weather conditions. In order to guarantee the precision and comparability of the results, the testing program necessitates that atmospheric parameters remain within predetermined boundaries.
These conditions are monitored using an atmospheric sounding probe on a Mi-8AMT helicopter. The probe is suspended on an external sling approximately 12 meters below the helicopter, enabling specialists to collect atmospheric measurements at the necessary altitudes and locations.
The information collected assists engineers in determining whether the current atmospheric conditions are appropriate for testing. The flights must be postponed if the temperature, humidity, or wind speed exceed the permitted limits.
Acoustic Measurement Requires Hundreds of Aircraft Passes
At the Ramenskoye airfield, the acoustic measurement infrastructure is deployed before the test flights begin. It consists of a network of microphones that are highly sensitive and are set up at designated measurement locations scattered throughout the runway.
Individual test flights are conducted by specialists who use between four and eight microphones, with multiple microphones installed at each measurement location. Additional sensors are positioned in close proximity to the surface to measure specific tonal components of aircraft noise, while some are mounted on platforms that are approximately 1.2 meters above the ground.
The aircraft’s sound is captured by the microphones as it passes overhead. The flight trajectory information, engine operating parameters, atmospheric measurements, and data from onboard systems are all synchronized with these recordings.
The resulting dataset is substantial. The measurement program has the capacity to produce approximately 2,000 microphone recordings, with the combined acoustic, meteorological, trajectory, and onboard data occasionally exceeding 100 gigabytes, as per UAC’s published information.
Additionally, a controlled environment is necessary for the measurement process. Recordings may be disrupted by unrelated noise; therefore, a special silence regime is implemented during testing. Other potentially disruptive activities, such as nearby construction work, may also be suspended, while air traffic control operations in the immediate vicinity of the airfield are coordinated accordingly.
The objective is to isolate the aircraft’s noise and obtain reliable measurements under precisely defined conditions.
Twelve Flights and Hundreds of Test Manoeuvres
More than 200 specialists from the Gromov Flight Research Institute and Yakovlev are involved in the SJ-100 acoustic certification program. The program is expected to consist of 12 flights, each of which will involve various take-off and landing maneuvers.
A single session may exceed three hours. Test pilots execute approximately 20 to 25 different flight regimes during this period, in compliance with meticulously established parameters.
The aircraft is required to maintain precise altitude, speed, engine thrust, and flight-path characteristics. It must also maintain a narrow tolerance in relation to the designated measurement points and the runway centerline.
These requirements are essential because the measured noise depends not only on engine operation but also on the aircraft’s speed, altitude, and trajectory. The maneuver must be repeated if an individual measurement is invalidated by even relatively small deviations.
The assessment also takes into account various engine operating conditions and landing configurations. The engines are not the only source of aircraft noise. The aggregate sound recorded on the ground is influenced by landing gear, wing high-lift devices, and other aerodynamic components.
This is the reason why engineers must assess the entire aircraft rather than merely measuring the acoustic characteristics of the PD-8 engine independently.
New Optical Technology Improves Flight-Path Accuracy
Specialists at the Gromov Flight Research Institute have developed the Mobile Optical Measurement Complex (MOK-I), a critical component of the SJ-100 testing program.
The system resolves a technical challenge that is linked to the acquisition of highly precise aircraft trajectory measurements. Interference can occur in conventional satellite navigation-based systems, which can complicate the maintenance of the precision necessary for certification flights.
MOK-I uses optical modules that are equipped with cameras that operate in the visible, infrared, and ultraviolet spectrums. The aircraft’s position and trajectory are reconstructed by specialized software that processes the video information captured by these cameras during flight.
The system is capable of observing aircraft from a distance of up to 20 kilometers, although its most precise trajectory measurements are obtained within a five-kilometer radius.
One of its critical capabilities is the real-time transmission of trajectory information to the test aircraft. Pilots can observe whether the aircraft is adhering to the necessary flight corridor and implement adjustments during the maneuver.
This minimizes the probability of invalid test passes and prevents the necessity of repeating costly flights due to the aircraft’s deviation from its intended trajectory.
The optical system augments the current onboard trajectory measurement equipment and offers engineers an additional method of monitoring the accuracy of flight tests.
Weather Limits the Available Testing Window
The program continues to be severely impacted by the weather. Acoustic testing necessitates a comparatively restricted set of atmospheric conditions, in contrast to numerous other aircraft certification activities.
The most suitable period in Russia typically stretches from late May to mid-October. Even during these months, only a small percentage of the available flying days satisfy the necessary meteorological criteria. UAC’s published account indicates that 40 to 50 days may be available during the season; however, only 20 to 30 percent of these days typically meet the criteria for valid acoustic measurements.
Measurements may be rendered invalid by temperature inversions, excessive wind, unsuitable cloud conditions, and precipitation. Consequently, the atmospheric sounding helicopter is crucial both before and during the testing program.
The aircraft may be required to return to the holding area while meteorological measurements are repeated if conditions alter during a test session. This guarantees that all results are recorded in accordance with the certification standards.
A Critical Phase of SJ-100 Certification
The acoustic program is implemented in conjunction with the PD-8 engine’s successful completion of its thorough certification testing. The United Engine Corporation announced the completion of the engine’s certification program in May 2026, citing over 6,500 hours of accumulated testing. The PD-8 type certificate was subsequently issued by Rosaviatsiya in June 2026.
Aviation certification specialists will assess the results of the acoustic tests and incorporate them into the aircraft’s certification documentation.
The result is meaningful beyond the Russian domestic market. Compliance with international aircraft noise standards is a critical prerequisite for airport operations in various countries. As a result, the acoustic certification of the SJ-100 is pertinent to both its domestic deployment and its prospective international operations.