Get FinancingPass Or Fail: How Jets Are Tested
Testing has always been vital to preparing a new aircraft for service, including especially commercial and business jets. And for good reason. Each time a jet takes flight, passenger, pilot, and crew safety are at stake. Whether it’s ground, flight, cabin, virtual, reliability, structural, performance, altitude, acceleration, or environmental, the list of tests that manufacturers conduct to validate an aircraft’s worthiness is exhaustive. Plenty of research and information illustrates the complexity, expense, hours, and technologies involved. Here’s a broad look at different tests jet manufacturers conduct on the path to aircraft certification.
The Extent Of Modern Testing
To understand how extensive modern jet test programs are you only need to look to Gulfstream’s new G500 business jet, which recently earned its FAA type and production certificates on the same day, or Gulfstream’s ultra-wide-body G600 business jet, which is expected to receive its FAA type certification later this year. At one point, Gulfstream had 10 test aircraft concurrently involved in the respective test programs. Gulfstream President Mark Burns said the G500 receiving both certificates in one day points to the thousands of lab hours and 5,000-plus flight hours Gulfstream poured into its development.
The G600, meanwhile, had completed 600-plus flights and 2,290-plus flight hours as of mid-August, the bulk of which occurred during a six-month global tour designed to test its readiness. As AviationWeek.com reported, the quick maturation the G600 showed during testing stemmed in part from a considerable investment Gulfstream made into computer-aided design (CAD), wind tunnel testing, and grounds labs for both aircraft that enabled completing numerous tests and validating projections and systems on the ground versus in flight.
Airbus’ “Iron Bird” test rig provides a similar example. While an Iron Bird such as the one it used for its A350 XWB (featuring 187 tons of scaffolding arranged in a skeletal frame shaped like the jet) may never fly, Airbus says “each Iron Bird is the precursor to an Airbus aircraft that does.” Airbus outfitted the A350 XWB Iron Bird with electrics, hydraulics, and flight controls to test and validate each major system. It used a separate “mini cockpit” to simulate flight, including in various environmental conditions. “Aircraft components that function well in isolated evaluations may react differently when operating in concert with other systems—a situation the Iron Bird, with its integrated testing of an aircraft’s systems, is ideally suited to identify,” Airbus says.
Engine Exams
Tests that simulate bird strikes, heavy rain, hail, ice, and extreme temperatures are among the many tests jet engines undergo. General Electric, for instance, uses 11 test stands covering an area equal to nine Central Parks at its Peebles Test Operation site in Ohio. The company says the 11 stands include four indoor test cells and seven outdoor stands. Seven of these can test engines capable of outputting 150,000 pounds of thrust.
GE says it tests about 1,600 engines annually at Peebles. GE’s Brian DeBruin runs the facility and says that while some tests are “relatively benign,” others are “quite damaging” but necessary to “prove that your engines are good.” Among these are tests for “blade-out incidents” in which broken fan blade fragments enter the engine. GE simulates this using remotely ignited plastic explosives. Elsewhere, GE uses up to 10 development engines to simulate bird strikes and hail, including by firing dead bird carcasses and golf ball-sized ice into the engines. Endurance tests, meanwhile, entail running the engines continuously for stretches to simulate years of service.
On its blog, Air France Industries’ KLM Engineering & Maintenance says it uses indoor and outdoor test facilities to simulate an engine ingesting debris, dust, sand, hail, snow, ice, huge water amounts, and other materials. On-wing tests, meanwhile, involve such tasks as verifying an engine is producing the required thrust, checking for vibrations and proper balance, and verifying all systems are leak-free. Overall, KLM says it tests roughly 200 engines a year, going through roughly 5,000 liters of jet fuel.
When Lightning Strikes
Dust, ice, rain, wind, lightning, extreme temperatures, and varying altitudes are among the conditions jets routinely encounter. Where altitude is concerned, NTS, a private test, inspection, and certification provider, notes that while airframes are pressurized to provide oxygen, there’s the potential of “explosive decompression” if the airframe fails. Thus, NTS tests for this and other altitude-related issues. NTS can test airframes from sea level to 100,000 feet in various simulated atmospheric conditions.
Environmental testing also can involve taking new jets to locations with extreme temperatures, such as Iqaluit in the Canadian Arctic, where Airbus has reportedly tested its commercial jets. Travel & Leisure reports that while Boeing’s simulated tests have improved greatly over time, it sometimes tests new aircraft in temperatures sinking as low as -50 degrees Fahrenheit.
Where lightning is concerned, numerous sources state that a commercial plane will experience one lightning strike on average annually. The Morgan-Botti Lightning Laboratory at Cardiff University in Wales works with Airbus on a number of joint research projects and has the capability to generate controlled lightning strikes “with currents up to 200,000 amps, more than five times that of an average lightning strike.” Boeing also maintains a 2-megavolt high-voltage generator and 50-to-60 kilovolts high-current system that produces 200,000 amps to simulate lightning impacts on jets in flight.