Chapter 4 Stethoscope and Electrocardiogram

The next morning, inside the Assembly Building.

Li Jianguo was staring intently at a Soviet Vacuum Tube Oscilloscope in front of him.

A straight, bright line appeared on the green circular fluorescent screen.

That was Channel A, connected to the pressure sensor.

"Pressure is 2.5 MPa; pressure holding is normal."

Li Jianguo wiped the oily sweat from his forehead and marked a heavy check in his notebook.

"I told you, those design folks just love to scare people. Cryogenic leakage? Isn't this thing as stable as a rock?"

Lin Xi grumbled internally: Stable, my ass. That's just because your sensor's precision isn't high enough; it's blind.

He leaned forward slightly, cleverly blocking Li Jianguo's peripheral vision.

At that moment, Li Jianguo reached down for the enamel tea mug at the edge of the table, his gaze leaving the screen for about three seconds.

The opportunity!

Lin Xi's heart raced, but his hands were incredibly steady.

He had practiced plugging and unplugging probes countless times in the laboratory of 2025; it had already become muscle memory.

His hand slipped out from his wide sleeve, bringing with it a bundle of enameled wire.

There was an extremely faint, crisp "click."

The piezoelectric ceramic piece with the magnet attached itself precisely to the first-stage engine's fuel delivery pipe.

Immediately after, the plug at the other end was thrust into the oscilloscope's idle "Input B" jack with lightning speed.

The movement was smooth and fluid, taking only 2.5 seconds.

[That hand speed! It's a solid fact that the Streamer has been single for twenty years!]

[Successful tower steal! No idea what he's doing, but it looks impressive.]

[High-energy alert ahead!]

Li Jianguo took a sip of strong tea, set down the mug, and looked up, his gaze returning to the oscilloscope.

Originally, he just intended to take one last routine look before shutting it down.

But that one look made the old man's eyes widen and his brow furrow.

On the screen that originally had only one straight line, there was now a frantically jumping green line—

That was the signal from Channel B.

Unlike the stability of Channel A, the line for Channel B was jumping like crazy!

Sharp, spiky waveforms exploded across the screen, forming sawtooth patterns.

"Hmm?"

Li Jianguo's hand paused as he was setting down the tea mug, which hit the table with a heavy "clang."

He reached out and slapped the metal casing of the oscilloscope, making a "slap-slap" sound.

This was the universal law of repairing electrical appliances in that era: give it a slap, and it'll be fine.

But this time, the waveform didn't disappear; instead, it jumped even more frantically, as if mocking his ignorance.

"This piece of junk, is it damp again?" Li Jianguo grumbled as he reached out to pull the wire.

"Where is this interference signal coming from..."

"Master!"

Lin Xi suddenly spoke. His voice wasn't loud, but it was perfectly timed to interrupt Li Jianguo's movement.

He wore a look of "innocent" curiosity.

He pointed at the screen like a studious schoolboy:

"Master, why is the line on Channel B jumping like crazy?"

"Is this oscilloscope broken?"

Li Jianguo glared at him.

"Go away, you don't know jack."

"This is power frequency interference. Probably the air compressor next door is leaking electricity... wait."

The old man's hand froze in mid-air.

If it were power frequency interference (mains power), the waveform should be a rounded, smooth sine wave with a fixed frequency of 50 Hz.

But this thing on the screen was sharp and piercing.

Moreover, the frequency was too fast, so dense that it was impossible to count.

Lin Xi timely glanced at the bottom left corner of his vision.

[Long Five Screw - Retired Version: The frequency is calculated! It's stable at 1240 Hz! This is the characteristic whistling frequency of high-pressure airflow striking micro-cracks in metal! It's the legendary 'Ghost Whistle'!]

[Physics Representative: Simply put, it's like blowing a whistle; the crack is the mouthpiece, and the high-pressure gas is the airflow!]

Lin Xi immediately transformed the wisdom of the bullet chat into his own "nonsense."

He scratched his head and said casually,

"Master, I don't think this looks like power frequency interference."

"I've seen the waveforms of power frequency interference in the school lab; those were big waves."

"Why is this all spikes?"

"And looking at this frequency... it must be over a thousand Hertz, right?"

"It's like someone's blowing a whistle."

"Blowing a whistle?"

Li Jianguo was stunned.

He had worked with machinery his whole life and had a near-instinctive intuition for vibrations.

Over a thousand Hertz? Airflow howling?

He suddenly turned his head and stared fixedly at Lin Xi.

"What did you just say, kid? Over a thousand Hertz?"

"Huh? I was just guessing blindly," Lin Xi said, shrinking his neck back with an innocent look.

"I just thought the sound of the air compressor blades just now sounded like this pitch..."

"Master, do you think something could be vibrating inside the pipe?"

"Something inside the pipe..." Li Jianguo murmured, his face instantly turning pale.

Under this pressure, if high-frequency vibration occurred within the pipeline, there was only one possibility—

A seal had failed, and the high-pressure airflow was repeatedly tearing at the O-ring like it was blowing up a balloon!

"Shut it down!"

Li Jianguo suddenly roared, his voice so loud that the nearby recorder dropped their pen in shock.

"Shut down all the air compressors for me!"

"Now! Everyone stop what you're doing!"

Subsequently, the workshop fell silent, leaving only the faint hum of the oscilloscope.

Even with the air compressors off, the pressure in the pipeline remained.

The waveform on Channel B continued to jump stubbornly, though its amplitude had decreased slightly. This only further proved—

This wasn't external interference; this was a scream from within the system.

"It's real..."

Li Jianguo's hands were shaking slightly.

He no longer slapped the machine but leaned in close to the sawtooth wave on the screen.

"It's not interference; there really is vibration."

He suddenly looked back, his eyes fixed on the Intern with a complex expression.

He then glanced at the laughably crude "ball of black tape" stuck to the pipe wall.

"Someone go get Deputy Chief Engineer Zhang, immediately! Run!"

...

Twenty minutes later, inside the General Command Room.

A group of gray-haired senior experts gathered around a table, the atmosphere heavy.

In the center of the table lay the rubber seal that had just been removed.

Under a German-imported optical microscope with dozens of times magnification, the truth was laid bare before everyone.

It was a gap nearly invisible to the naked eye.

"That was close..." one expert said, removing his glasses, his voice trembling.

"With this kind of damage, the sealing is fine at room temperature."

"But with the temperature dropping to minus 30 degrees these past two days, the rubber hardens, and this crack will burst open immediately."

"Once it bursts, it's a propellant leak," the propulsion system expert beside him said, his face ashen.

"In just twenty-six seconds, the combustion chamber would explode into fragments due to pressure imbalance."

Dead silence.

Everyone felt a wave of lingering fear.

It was so close.

If not for that "faulty" oscilloscope, if not for that "meddlesome" Intern...

In three days, this place would have been a sea of fire.

"Investigate!" Deputy Chief Designer Elder Zhang slammed his fist on the table, making the teacup lid rattle.

"Who performed the quality inspection on this seal?"

"And who installed that Channel B probe that discovered the problem?"